Medical terms - Letter X | MedicalVocabulary.org

X (drug caution code)

Abbreviation on a medication that indicates SOS -- that the medication contains a substance such as acetaminophen that could cause problems -- consult your pharmacist. While not a part of the historical heritage of…
X (in genetics)

Although the letter X can be used as a symbol in various ways (such as with X-rays, the X-axis of a graph, etc.), 'the X ' in genetics and medicine today usually refers to the X chromosome. The X is the sex chromosome…
X chromosome

A sex chromosome found in both females and males. Normal females usually have two X chromosomes. Normal males usually have one X along with a Y chromosome. The complete chromosome complement consisting of 46 chromosomes…
X chromosome inactivation

See: X inactivation
X inactivation

The phenomenon in a female by which one X chromosome (either the maternally or paternally derived X) is randomly (by chance) inactivated in an early embryonic cell, with fixed inactivation of that same X in all cells…
X, factor

A coagulation factor, a substance in blood essential to the normal clotting process. Production of factor X takes place in the liver and requires vitamin K. The gene for factor X is located on chromosome 13 and is in…
X-linked

On the X chromosome. 'Linked' in genetics does not mean merely associated. An X-linked gene travels with the X chromosome and therefore is part of the X chromosome.
X-linked juvenile retinoschisis

See: Juvenile retinoschisis
X-linked retinoschisis

See: Juvenile retinoschisis
X-ray

1. High-energy radiation with waves shorter than those of visible light. X-rays possess the properties of penetrating most substances (to varying extents), of acting on a photographic film or plate (permitting…
X-ray crystallography

The use of X-rays of known wavelength to learn the structure of any crystalline material. Put otherwise, X-ray crystallography is a technology by which the locations of atoms in any crystal can be precisely mapped by…
X-ray, AP

An X-ray picture in which the beams pass from front-to-back (anteroposterior). An AP film is as opposed to a PA (posteroanterior) film in which the rays pass through the body from back-to-front
X-ray, lateral

An X-ray picture taken from the side
X-ray, PA

An X-ray picture in which the beams pass from back-to-front (posteroanterior). By contrast an AP (anteroposterior) film is one in which the rays pass through the body from front-to-back
X-rays during pregnancy

See: Prenatal radiation exposure
Xanax

See: Alprazolam
Xanth- (prefix)

A colorful prefix relating to a yellow color. 'Xanth-' is related to the word 'xanthic' which has its roots in the Greek word 'xanthos' which means yellow. A number of medical terms trace to 'xanthos' including, for…
Xanthelasma

Tiny (1-2 mm) yellowish plaques that are slightly raised on the skin surface of the upper or lower eyelids. Xanthelasma is caused by tiny deposits of fat in the skin and is often associated with abnormal blood fat…
Xanthine

A substance found in caffeine, theobromine, and theophylline and encountered in tea, coffee, and the colas. Chemically, xanthine is a purine. There is a genetic disease of xanthine metabolism, xanthinuria, due to…
Xanthinuria

An inherited metabolic disorder in which there is deficiency of an enzyme needed to process xanthine, a substance found in caffeine, theobromine, theophylline, and related substances. Unchecked, xanthinuria can lead to…
Xanthoma

Yellowish firm nodules in the skin frequently indicating underlying disease, such as diabetes, disorder of fats (lipid disorder or hyperlipidemia), or other conditions. A xanthoma is a kind of harmless growth of tissue…
Xanthoma tendinosum

Xanthoma that clusters around tendons, and is associated with lipid disorders
Xanthoma tuberosum

Xanthoma that clusters near joints. It is associated with lipid disorders, cirrhosis of the liver, and thyroid disorders
Xanthoma, diabetic

See: Eruptive xanthoma
Xanthoma, disseminatum

A type of xanthoma characterized by orange-to-brown nodules on the skin or mucus membranes
Xanthoma, eruptive

See: Eruptive xanthoma
Xanthoma, planar

A type of xanthoma characterized by flat yellow-to-orange patches or pimples that cluster together on the skin
Xanthomatosis

A condition in which fatty deposits occur in various parts of the body. These fatty deposits are called xanthomas or xanthomata and appear as yellowish firm nodules in the skin. Xanthomas are in themselves a harmless…
Xanthopsia

A form of chromatopsia, a visual defect in which objects appear as if they have been overpainted with an unnatural color. In xanthopsia, that color is yellow
Xanthosis

Yellowing of the skin without yellowing of the eyes. In jaundice there is yellowing of both the skin and the whites of the eyes. Xanthosis is associated sometimes with malignancies
Xen- (prefix)

Foreign or other. As in: > >Xenoantigen -- An antigen that is found in more than one species. >Xenograft -- A surgical graft of tissue from one species to an unlike species, genus or family. >Xenotransplantation --…
Xeno- (prefix)

Foreign or other. As in: > >Xenoantigen -- An antigen that is found in more than one species. >Xenograft -- A surgical graft of tissue from one species an unlike species, genus or family. >Xenotransplantation --…
Xenoantigen

An antigen that is found in more than one species. An antigen is something that is capable of inducing an immune response. The prefix 'xeno-' means foreign or other. It comes from the Greek 'xenos' meaning stranger…
Xenobiotic

Natural substances that are foreign to the body
Xenograft

A surgical graft of tissue from one species to an unlike species (or genus or family). A graft from a baboon to a human is a xenograft. The prefix 'xeno-' means foreign. It comes from the Greek word 'xenos' meaning…
Xenotransplantation

Transplantation from one species to a foreign one. The rationale for xenotransplantation has included the short supply of human organs for transplantation. The first surgeon to do an animal-to-human heart transplant was…
Xenotropic virus

A virus that can grow in the cells of a species foreign to the normal host species, a species different from that which normally hosts it. Xeno- means foreign while -tropic refers to growth. So xeno- + -tropic = capable…
Xeric

Characterized by a scanty supply of moisture (or tolerating or adapted to dry conditions). The word 'xeric' is derived from 'xeros,' the Greek word for 'dry.' 'Xeric' was coined in 1926 and was in common scientific…
Xero-

Fix): Dry. From the Greek 'xeros' meaning 'dry.' Examples of words containing 'xero-' -- xeroderma is dry skin; xerophagia is eating a dry diet; xerophthalmia is dry eye; and xerostomia.
Xeroderma

Abnormally dry skin. Xeroderma can be caused by a deficiency of vitamin A, systemic illness, overexposure to sunlight, or medication. It can usually be addressed by the use of over-the-counter (OTC) topical…
Xeroderma pigmentosum

A genetic disease characterized by such extraordinary sensitivity to sunlight that it results in the development of skin cancer at a very early age. Children with xeroderma pigmentosum (XP) can only play outdoors safely…
Xerogram

A picture of the body recorded on paper rather than on film. Also called a xeroradiograph. From the Greek 'xeros' meaning 'dry.'
Xeromammography

Xeroradiography of the breast. Xeroradiography is a photoelectric method of recording an x-ray image on a coated metal plate, using low-energy photon beams, long exposure time and dry chemical developers. The prefix…
Xerophagia

A dry diet. Literally, dry eating. From the Greek 'xeros' meaning 'dry' + 'phago' meaning 'to eat.
Xerophthalmia

Dry eyes. Xerophthalmia can be associated with systemic diseases such as Sjogren' s syndrome, systemic lupus erythematosus, rheumatoid arthritis, scleroderma, sarcoidosis, amyloidosis, and hypothyroidism; deficiency of…
Xeroradiograph

A picture of the body recorded on paper rather than on film. Also called a xerogram. From the Greek 'xeros' meaning 'dry.'
Xeroradiography

The process of making a type of dry x-ray in which a picture of the body is recorded on paper rather than on film
Xerosis

Abnormal dryness of the skin (xeroderma), of the conjunctiva of the eye (xerophthalmia), or of the mucous membranes such as dry mouth (xerostomia). The word 'xerosis' literally means 'dry condition.' It was compounded…
Xerostomia

Dry mouth. The condition of not having enough saliva to keep the mouth wet due to inadequate function of the salivary glands. Everyone has a dry mouth once in a while when they are nervous, upset or under stress. But if…
Xiphoid process

A pointed cartilage attached to the lower end of the breastbone or sternum, the smallest and lowest division of the sternum. Cartilaginous early in life, it may become ossified (bony) in adults. It is sometimes simply…