X

Symbol for Kienböck unit; xanthosine; halogen atom; unspecified amino acid.

X
X

Symbol for reactance.

Xaa
Xaa

Symbol for unspecified amino acid.

Xan
Xan

Abbreviation for xanthine.

xanth- xanth-

See xantho-.

xanthelasma
xanthelasma (zan-the-laz′ma)

SYN: x. palpebrarum. [xanth- + G. elasma, a beaten metal plate]
generalized x. xanthoma planum of the neck, trunk, extremities, and eyelids in patients with normal plasma lipid levels.
x. palpebrarum soft, yellow-orange plaques on the eyelids or medial canthus, the most common form of xanthoma; may be associated with low-density lipoproteins, especially in younger adults. SYN: x., xanthoma palpebrarum.

xanthematin
xanthematin (zan-them′a-tin)

A yellow substance derived from hematin by treating with nitric acid.

xanthemia
xanthemia (zan-the′me-a)

SYN: carotenemia. [xanth- + G. haima, blood]

xanthene
xanthene (zan′then)

1. The basic structure of many natural products, drugs, dyes ( e.g., fluorescein, pyronin, eosins), indicators, pesticides, antibiotics, etc. 2. A class of molecules based upon x. (1).

xanthic
xanthic (zan′thik)

1. Yellow or yellowish in color. 2. Relating to xanthine.

xanthidylic acid
xanthidylic acid (zan′thi-dil-ik)

SYN: xanthosine 5′-monophosphate.

xanthine
xanthine (Xan) (zan′then)

2,6-Dioxopurine; 2,6-(1H,3H)-purinedione;oxidation product of guanine and hypoxanthine, precursor of uric acid; occurs in many organs and in the urine, occasionally forming urinary calculi; elevated in molybdenum cofactor deficiency and in xanthinuria.
x. dehydrogenase an oxidoreductase oxidizing x. to urate with NAD⁺ as the oxidant; lower activity in individuals with a deficiency of molybdenum cofactor.
x. nucleotide SYN: xanthosine 5′-monophosphate.
x. oxidase a flavoprotein containing molybdenum; an oxidoreductase catalyzing the reaction of x., O₂, and H₂O to produce urate and superoxide; also oxidizes hypoxanthine, some other purines and pterins, and aldehydes. A lower activity is observed in molybdenum cofactor deficiency. SYN: hypoxanthine oxidase, Schardinger enzyme.
x. ribonucleoside SYN: xanthosine.

xanthinol niacinate
xanthinol niacinate, xanthinol nicotinate (zan′thi-nol)

A peripheral vasodilator.

xanthinuria
xanthinuria (zan-thi-noo′re-a)

1. Excretion of abnormally large amounts of xanthine in the urine. 2. A disorder [MIM*278300], characterized by urinary excretion of xanthine in place of uric acid, hypouricemia, and occasionally the formation of renal xanthine stones. There are two types: type I is due to xanthine dehydrogenase deficiency (XDH), and type II is due to deficiencies of both xanthine dehydrogenase and aldehyde oxidase. Autosomal recessive inheritance, caused by mutation in the XDH gene on chromosome 2p in some cases. SYN: xanthiuria, xanthuria. [xanthine + G. ouron, urine]

xanthism
xanthism (zan′thizm) [MIM*278400]

A pigmentary anomaly of blacks, characterized by red or yellow-red hair color, copper-red skin, and often by dilution of iris pigment; autosomal recessive inheritance caused by mutation in the tyrosinase-related protein 1gene (TYRP1) on chromosome 9. SYN: rufous albinism. [G. xanthos, yellowish]

xanthiuria
xanthiuria (zan-the-u′re-a)

SYN: xanthinuria.

xantho- xantho-, xanth-

Yellow, yellowish. [G. xanthos]

xanthoastrocytoma
xanthoastrocytoma (zan′thro-as′tro-si-to- ma)

SYN: pleomorphic x.. [xantho + astrocytoma]
pleomorphic x. a rare variant of astrocytoma usually presenting early in life with seizures. The tumor is superficially located and composed of pleomorphic glial cells, lipidized astrocytes, and perivascular lymphocytes. SYN: x..

xanthochromatic
xanthochromatic (zan′tho-kro-mat′ik)

Yellow-colored. SYN: xanthochromic.

xanthochromia
xanthochromia (zan-tho-kro′me-a)

The occurrence of patches of yellow color in the skin, resembling xanthoma, but without the nodules or plates. SYN: xanthoderma (1) , yellow disease, yellow skin (1) . [xantho- + G. chroma, color]

xanthochromic
xanthochromic (zan-tho-kro′mik)

SYN: xanthochromatic.

xanthoderma
xanthoderma (zan-tho-der′ma)

1. SYN: xanthochromia. 2. Any yellow coloration of the skin. SYN: yellow skin (2) . [xantho- + G. derma, skin]

xanthodont
xanthodont (zan′tho-dont)

One who has yellow teeth. [xantho- + G. odous, tooth]

xanthogranuloma
xanthogranuloma (zan′tho-gran′u-lo′ma)

A peculiar infiltration of retroperitoneal tissue by lipid macrophages, occurring most commonly in women.
juvenile x. single or multiple reddish to yellow papules or nodules, usually found in young children, consisting of dermal infiltration by histiocytes and Touton giant cells, with increasing fibrosis. SYN: nevoxanthoendothelioma.
necrobiotic x. a cutaneous and subcutaneous x. with focal necrosis, presenting as multiple large, sometimes ulcerated, red to yellow granulomatous nodules with giant cells (often around the eyes) associated with paraproteinemia (usually monoclonal gammopathy).

xanthogranulomatous
xanthogranulomatous (zan′tho-gran′u-lo′ma-tus)

Relating to, of the nature of, or affected by xanthogranuloma.

xanthoma
xanthoma (zan-tho′ma)

A yellow nodule or plaque, especially of the skin, composed of lipid-laden histiocytes. [xantho- + G. -oma, tumor]
x. diabeticorum eruptive x. associated with severe diabetes.
x. disseminatum a rare benign normolipemic disorder of adults with coalescent cutaneous xanthomas composed of non-X histiocytes on flexural surfaces, often with mild diabetes insipidus.
eruptive x. the sudden appearance of groups of 1–4-mm waxy yellow or yellowish-brown papules with an erythematous halo, especially over extensors of the elbows and knees, and on the back and buttocks of patients with severe hyperlipemia, often familial or, more rarely, in severe diabetes.
fibrous x. fibroxanthoma.
x. multiplex SYN: xanthomatosis.
x. palpebrarum SYN: xanthelasma palpebrarum.
x. planum a form marked by the occurrence of yellow, flat bands or minimally palpable rectangular plates in the corium, either normolipemic or associated with type IIa or III hyperlipoproteinemia.
tendinous x. x. involving tendons, ligaments, and fascia, forming deep, smooth, sometimes painful nodules beneath normal-appearing freely movable skin of the extremities; associated with abnormal lipid metabolism, commonly familial increased β lipoproteins, or obstructive liver disease.
x. tuberosum xanthomatosis associated with familial type II, and occasionally type III, hyperlipoproteinemia. SYN: x. tuberosum simplex.
x. tuberosum simplex SYN: x. tuberosum.
verrucous x. histocytosis Y; a papilloma of the oral mucosa and skin in which squamous cell epithelium covers connective tissue papillae filled with large foamy histiocytes. SYN: histiocytosis Y.

xanthomatosis
xanthomatosis (zan-tho-ma-to′sis)

Widespread xanthomas, especially on the elbows and knees, that sometimes affect mucous membranes and are sometimes associated with metabolic disturbances. SYN: lipid granulomatosis, lipoid granulomatosis, xanthoma multiplex.
biliary x. x. with hypercholesterolemia, resulting from biliary cirrhosis. SYN: Rayer disease.
x. bulbi ulcerative fatty degeneration of the cornea after injury.
cerebrotendinous x. [MIM*213700] a metabolic disorder associated with deposition of cholestanol and cholesterol in the brain and other tissues; plasma cholestanol level is high but plasma cholesterol level is normal; characterized by progressive cerebellar ataxia beginning after puberty, cataracts, spinal cord involvement, premature atherosclerosis, and tendinous or tuberous xanthomata; due to a defect in hepatic mitochondrial sterol 27-hydroxylase in bile acid biosynthesis; autosomal recessive inheritance, caused by mutation in the gene involved in cytochrome P-450 in the C27 position (CYP27) on chromosome 2q.
chronic idiopathic x. vague or indefinite term for inherited abnormalities of lipid metabolism leading to xanthoma formation ( e.g., primary familial x.).
familial hypercholesteremic x. See type II familial hyperlipoproteinemia.
generalized plane x. widespread x. associated with multiple myeloma, familial hyperlipoproteinemia, or less commonly with primary biliary cirrhosis or no underlying disease.
normal cholesteremic x. SYN: Hand-Schüller-Christian disease.
Wolman x. SYN: cholesterol ester storage disease.

Xanthomonas
Xanthomonas (zan-tho-mo′as)

Genus of the family Pseudomonadaceae; aerobic, Gram-negative, chemoorganotrophic, straight bacilli that exhibit motility by flagella. Type species is X. campestris.
X. maltophilia a species found primarily in clinical specimens but also in water, milk, and frozen food; frequent cause of infections in hospitalized and immunocompromised humans, it is resistant to many commonly used antibiotics; formerly called Pseudomonas maltophilia. See Stenotrophomonas maltophilia.

xanthophyll
xanthophyll (zan′tho-fil)

Oxygenated derivative of carotene; a yellow plant pigment, occurring also in egg yolk and corpus luteum. SYN: lutein (2) , luteol, luteole.

xanthoproteic
xanthoproteic (zan-tho-pro′te-ik)

Relating to xanthoprotein.

xanthoproteic acid
xanthoproteic acid

A noncrystallizable yellow substance derived from proteins upon treatment with nitric acid.

xanthoprotein
xanthoprotein (zan-tho-pro′ten)

The yellow product formed upon treating protein with hot nitric acid, probably from nitration of phenyl groups.

xanthopsia
xanthopsia (zan-thop′se-a)

A condition in which objects appear yellow; may occur in picric acid and santonin poisoning, in jaundice, and in digitalis intoxication. SYN: yellow vision. [xantho- + G. opsis, vision]

xanthopuccine
xanthopuccine (zan-tho-puk′sen)

SYN: canadine.

xanthosine
xanthosine (X, Xao) (zan′tho-sen, -sin)

9-β-d-Ribosylxanthine;the deamination product of guanosine (O replacing –NH₂). SYN: xanthine ribonucleoside.
x. 5′-monophosphate (XMP) the monophosphoric ester of x.; an intermediate in GMP biosynthesis. SYN: xanthidylic acid, xanthine nucleotide, xanthylic acid.
x. 5′-triphosphate (XTP) x. with a triphosphoric acid esterified at its 5′ position.

xanthosis
xanthosis (zan-tho′sis)

A yellowish discoloration of degenerating tissues, especially seen in malignant neoplasms. [xantho- + G. -osis, condition]

xanthous
xanthous (zan′thus)

Yellowish; yellow-colored. [G. xanthos, yellow]

xanthurenic acid
xanthurenic acid (zan-thoo-ren′ik)

The sulfur-yellow crystals form a red compound with Millon reagent, or an intensely green one with ferrous sulfate; excreted in the urine of pyridoxine-deficient animals after the ingestion of tryptophan, and of rats fed almost exclusively with fibrin.

xanthuria
xanthuria (zan-thoo′re-a)

SYN: xanthinuria.

xanthyl
xanthyl (zan′thil)

A radical consisting of xanthine minus a hydrogen atom.

xanthylic
xanthylic (zan-thil′ik)

Relating to xanthine.

xanthylic acid
xanthylic acid

SYN: xanthosine 5′-monophosphate.

Xao
Xao

Symbol for xanthosine.

Xe
Xe

Symbol for xenon.

133Xe
¹³³Xe

Symbol for xenon-133.

xemilofiban
xemilofiban (zem-il-of′i-ban)

A novel antiplatelet agent that blocks the binding of fibrinogen to specific membrane GPIIb/IIIa integrin receptors and thus prevents platelet aggregation induced by any known platelet agonist.

xeno- xeno-

Strange; foreign material; parasite. See hetero-, allo-. [G. xenos, guest, host, stranger, foreign]

xenobiotic
xenobiotic (zen′o-bi-ot′ik)

1. A pharmacologically, endocrinologically, or toxicologically active substance not endogenously produced and therefore foreign to an organism. 2. Pertaining to association of two animal species, usually insects, in the absence of a dependency relationship, as opposed to parasitism. [xeno- + G. bios, life + -ic]

xenodiagnosis
xenodiagnosis (zen′o-di-ag-no′sis)

1. A method of diagnosing acute or early Trypanosoma cruzi infection (Chagas disease) in humans. Infection-free (laboratory-reared) triatomine bugs are fed on the tissue of the suspected person and the trypanosome is identified by microscopic examination of the intestinal contents of the bug after a suitable incubation period. 2. A similar method of biologic diagnosis based upon experimental exposure of a parasite-free normal host capable of allowing the organism in question to multiply, enabling it to be more easily and reliably detected.

xenogeneic
xenogeneic (zen′o-je-ne′ik)

Heterologous, with respect to tissue grafts, especially when donor and recipient belong to widely separated species. SYN: xenogenic (2) , xenogenous (2) . [xeno- + G. -gen, producing]

xenogenic
xenogenic (zen-o-jen′ik)

1. Originating outside of the organism, or from a foreign substance that has been introduced into the organism. SYN: xenogenous (1) . 2. SYN: xenogeneic. [xeno- + G. -gen, producing]

xenogenous
xenogenous (ze-noj′e-nus)

1. SYN: xenogenic (1) . 2. SYN: xenogeneic.

xenograft
xenograft (zen′o-graft)

A graft transferred from an animal of one species to one of another species. SYN: heterograft, heterologous graft, heteroplastic graft, xenogeneic graft.

xenon
xenon (Xe) (ze′non)

A gaseous element, atomic no. 54, atomic wt. 131.29; present in minute proportion (0.087 ppm) in the dry atmosphere; produces general anesthesia in concentrations of 70 vol.%. [G. xenos, a stranger]

xenon-133
xenon-133 (¹³³Xe)

A radioisotope of xenon with a gamma emission at 81 keV and a physical half-life of 5.243 days; used in the study of pulmonary function and organ blood flow.

xenoparasite
xenoparasite (zen-o-par′a-sit)

An ecoparasite that becomes pathogenic in consequence of weakened resistance on the part of its host.

xenophobia
xenophobia (zen-o-fo′be-a)

Morbid fear of strangers. [xeno- + G. phobos, fear]

xenophonia
xenophonia (zen-o-fo′ne-a)

A speech defect marked by an alteration in accent and intonation. [xeno- + G. phone, voice]

Xenopsylla
Xenopsylla (zen-op-sil′a)

The rat flea; a genus of fleas parasitic on the rat and involved in the transmission of bubonic plague. The species X. cheopis serves as a potent vector of Yersinia pestis, largely because its gut becomes “blocked” by a mass of Y. pestis cells that prevents the flea from feeding normally, so that it is inclined to attack humans and other hosts; it is an important source of infection in traditional epidemic areas such as India. X. astia and X. braziliensis are also efficient vectors of plague. [xeno- + G. psylla, flea]

xenyl
xenyl (zen′il)

A radical consisting of biphenyl minus a hydrogen atom.

xeransis
xeransis (ze-ran′sis)

A gradual loss of moisture in the tissues. [G. x., fr. xeros, dry]

xerantic
xerantic (ze-ran′tik)

Denoting xeransis.

xerasia
xerasia (ze-ra′ze-a)

A condition of the hair characterized by dryness and brittleness. [G. x., fr. xeros, dry]

xero- xero-

Dry. [G. xeros]

xerochilia
xerochilia (zer-o-ki′le-a)

Dryness of lips. [xero- + G. cheilos, lip]

xeroderma
xeroderma (zer′o-der′ma)

A mild form of ichthyosis characterized by excessive dryness of the skin due to slight increase of the horny layer and diminished water content of the stratum corneum from decreased perspiration, wind, or low humidity; seen with aging, atopic dermatitis, vitamin A deficiency, etc. [xero- + G. derma, skin]
x. pigmentosum [MIM*278700] an eruption of exposed skin occurring in childhood and characterized by photosensitivity with severe sunburn in infancy and the development of numerous pigmented spots resembling freckles, larger atrophic lesions eventually resulting in glossy white thinning of the skin surrounded by telangiectases, and multiple solar keratoses that undergo malignant change at an early age; results from several rare autosomal recessive complementation groups in which DNA repair processes are defective, so that they are more liable to chromosome breaks and cancerous change when exposed to ultraviolet light. Severe ophthalmic and neurologic abnormalities are also found. SEE ALSO: De Sanctis-Cacchione syndrome.

xerogram
xerogram (ze′ro-gram)

SYN: xeroradiograph.

xerography
xerography (zer-og′ra-fe)

SYN: xeroradiography.

xeroma
xeroma (ze-ro′ma)

SYN: xerophthalmia.

xeromammography
xeromammography (zer′o-mam-og′ra-fe)

Examination of the breast by xeroradiography.

xeromenia
xeromenia (zer-o-me′ne-a)

Obsolete term for occurrence of the usual constitutional symptoms at the menstrual period without any show of blood. [xero- + G. meniaia, menses]

xeromycteria
xeromycteria (zer′o-mik-ter′e-a)

Extreme dryness of the nasal mucous membrane. [xero- + G. mykter, the nose]

xerophagia
xerophagia, xerophagy (zer-o-fa′je-a, zer-of′a-je)

The eating of dry foodstuffs; subsisting on a dry diet. [xero- + G. phago, to eat]

xerophthalmia
xerophthalmia (zer-of-thal′me-a)

Excessive dryness of the conjunctiva and cornea, which lose their luster and become keratinized; may be due to local disease or to a systemic deficiency of vitamin A. SYN: conjunctivitis arida, xeroma, xerophthalmus. [xero- + G. ophthalmos, eye]

xerophthalmus
xerophthalmus (zer′of-thal′mus)

SYN: xerophthalmia.

xeroradiograph
xeroradiograph (ze-ro-ra′de-o-graf)

The permanent record made by xeroradiography. SYN: xerogram.

xeroradiography
xeroradiography (ze′ro-ra′de-og′ra-fe)

Radiography using a specially coated charged plate instead of x-ray film, developing with a dry powder rather than liquid chemicals, and transferring the powder image onto paper for a permanent record; edge enhancement is inherent. SYN: xerography.

xerosis
xerosis (ze-ro′sis)

Pathologic dryness of the skin (xeroderma), the conjunctiva (xerophthalmia), or mucous membranes. [xero- + G. -osis, condition]
x. parenchymatosus superficial drying of the conjunctiva due to diffuse scarring, with closure of the lacrimal gland openings.

xerostomia
xerostomia (zer′o-sto′me-a)

A dryness of the mouth, having a varied etiology, resulting from diminished or arrested salivary secretion, or asialism. [xero- + G. stoma, mouth]

xerotic
xerotic (ze-rot′ik)

Dry; affected with xerosis.

xerotripsis
xerotripsis (zer-o-trip′sis)

Dry friction. [xero- + G. tripsis, a rubbing, fr. tribo, to rub]

Xg blood group
Xg blood group

See Blood Groups appendix.

X-inactivation
X-inactivation

SYN: lyonization.

xiph- xiph-

See xipho-.

xiphisternal
xiphisternal (zif-i-ster′nal)

Relating to the xiphoid process.

xiphisternum
xiphisternum (zif′i-ster′num)

SYN: xiphoid process. [xiphoid + G. sternon, chest]

xipho- xipho-, xiph-, xiphi-

Xiphoid, usually the processus xyphoideus. [G. xiphos, sword]

xiphocostal
xiphocostal (zif′o-kos′tal)

Relating to the xiphoid process and the ribs. [xipho- + L. costa, rib]

xiphodynia
xiphodynia (zif-o-din′e-a)

Pain of a neuralgic character, in the region of the xiphoid cartilage. SEE ALSO: hypersensitive xiphoid syndrome. SYN: xiphoidalgia. [xipho- + G. odyne, pain]

xiphoid
xiphoid (zi′foyd) [TA]

Sword-shaped; applied especially to the x. process. SYN: ensiform, gladiate, mucronate. [xipho- + G. eidos, appearance]

xiphoidalgia
xiphoidalgia (zif-oy-dal′je-a)

SYN: xiphodynia. [xiphoid + G. algos, pain]

xiphoiditis
xiphoiditis (zif′oy-di′tis)

Inflammation of the xiphoid process of the sternum. [xiphoid + G. -itis, inflammation]

xiphopagus
xiphopagus (zi-fop′a-gus)

Conjoined twins united in the region of the xiphoid process of the sternum. See conjoined twins, under twin. [xipho- + G. pagos, something fixed]

X-linked
X-linked

Pertaining to genes borne on the X chromosome. Commonly but erroneously used synonymously with sex-linked, which would also comprise Y-linked traits.

XMP
XMP

Abbreviation for xanthosine 5′-monophosphate.

x-omat
x-omat (eks′o-mat)

A trade name (of Kodak) that has become the generic designation of an automatic processor for x-ray films.

x-radiation
x-radiation

Radiant energy from an x-ray tube. SEE ALSO: x-ray.

x-ray
x-ray

1. The ionizing electromagnetic radiation emitted from a highly evacuated tube, resulting from the excitation of the inner orbital electrons by the bombardment of the target anode with a stream of electrons from a heated cathode. SYN: roentgen ray. Cf.:glass rays, under ray, indirect rays, under ray. 2. Ionizing electromagnetic radiation produced by the excitation of the inner orbital electrons of an atom by other processes, such as nuclear delay and its sequelae. 3. SYN: radiograph.

XTP
XTP

Abbreviation for xanthosine 5′-triphosphate.

Xy
Xy

Abbreviation for xylose.

Xyl
Xyl

Abbreviation for xylose.

xyl- xyl-, xylo-

Wood, woody; xylose, xylene. [G. xylon]

xylazine
xylazine (zi′la-zen)

A sedative/hypnotic/anesthetic widely used in veterinary medicine and in laboratory animals.

xylene
xylene (zi′len)

SYN: xylol.
x. cyanol FF [C.I. 43535] an acidic triphenylmethane dye used for histochemical staining of hemoglobin peroxidase and as a tracking dye for DNA sequencing in electrophoresis.

xylenol
xylenol (zi′le-nol)

Occurring in six isomeric forms; used in the manufacture of coal tar disinfectants and synthetic resins. SYN: dimethylphenol.

xylidine
xylidine (zi′li-den)

Aminodimethylbenzene;used as a reagent and in the manufacture of dyes.

xylitol
xylitol (zi′li-tol)

An optically inactive sugar alcohol; often used as a sugar substitute in diabetic diets; the synthesis of x. from l-xylulose is blocked in individuals with idiopathic pentosuria.

xylitol dehydrogenase
xylitol dehydrogenase

SYN: xylulose reductase.

xylo- xylo-

See xyl-.

xylobiose
xylobiose (zi′lo-bi′os)

A disaccharide of two xylose residues linked β1→4, both in pyranose rings.

xyloidin
xyloidin (zi-loy′din)

SYN: pyroxylin.

xyloketose
xyloketose (zi-lo-ke′tos)

SYN: xylulose.

xylol
xylol (zi′lol)

A volatile liquid obtained from coal tar, having physical and chemical properties similar to those of benzene; it occurs as three isomers; m-, o-, and p-x.; used as a solvent, in the manufacture of chemicals and synthetic fibers, and in histology as a clearing agent. SYN: dimethylbenzene, xylene.

xylometazoline hydrochloride
xylometazoline hydrochloride (zi′lo-me-taz′o-len)

A sympathomimetic drug used as a nasal decongestant.

xylonic acid
xylonic acid (zi′lon-ik)

A mild oxidation product of xylose.

xylopyranose
xylopyranose (zi-lo-pir′a-nos)

Xylose in pyranose form.

xylose
xylose (Xy, Xyl) (zi′los)

An aldopentose, isomeric with ribose, obtained by fermentation or hydrolysis of naturally occurring carbohydrate substances, e.g., in wood fiber. An important dietary component for herbivores. The d-isomer is also known as wood or beechwood sugar. SYN: uridine diphosphoxylose.

xylulose
xylulose (zi′loo-los)

threo-Pentulose;a 2-ketopentose. l-X. appears in the urine in cases of essential pentosuria; it is also an intermediate in the glucuronate pathway. SYN: xyloketose.
x. 5-phosphate the d-isomer is an intermediate in the pentose phosphate pathway and in transketolization.
x. reductase an enzyme that reversibly converts x. to xylitol using either NADH (d-x. reductase) or NADPH (l-x. reductase); a deficiency of the l form is seen in individuals with essential pentosuria. SYN: xylitol dehydrogenase.

xylyl
xylyl (zi′lil)

The radical consisting of xylene (xylol) minus a hydrogen atom.
x. bromide the o-, m-, and p-forms are powerful lacrimators.

xylylene
xylylene (zi′li-len)

The radical consisting of xylene (xylol) minus two hydrogen atoms.

xysma
xysma (ziz′ma)

Membranous shreds in the feces. [G. filings, shavings, fr. xyo, to scrape]