Medical prefix: A prefix employed in medical terminology. Medical words are often put together, cobbled from two or more building blocks. Among these building blocks are the prefixes.

Examples of prefixes used in medicine include:

• a-: Prefix much employed in the health sciences indicating "not, without, -less" as, for examples, in alexia (not read), aphagia (not eat), aphonia (not voice, voiceless). The "a-" usually becomes "an-" before a vowel as, for example, in anemia (without blood), anotia (no ear), anoxia (no oxygen). The prefix "a-" comes from the Greek meaning "not."


• ab-: Prefix from the Latin meaning "from, away from, off" as in abduction (movement of a limb away from the midline of the body), ablate (carry or cut away), abnormal (away from normal), absorb (to suck away). "Abs" in the plural is slang for the abdominal muscles.


• ad-: Latin prefix meaning "toward" and "in the direction of" (among other things), As, for example, in adduction (movement of a limb toward the midline of the body), adrenal (toward the kidney).


• alb-: Prefix from the Latin root for the color white, "albus." As in albino and albinism. The term "albino" was first applied by the Portuguese to "white" people they encountered in West Africa. Those "white" people probably had partial or complete albinism, an inherited lack of pigment in the skin, hair, and eyes.


• colpo-: A combining form usually used as a prefix from the Greek "kolpos" meaning a fold, cleft, or hollow, often in reference to the vagina. Words incorporating colpo- include colposcopy (examination of the vagina and cervix with a colposcope) and colpotomy (incision of the vagina).


• dextro-: From the Latin "dexter" meaning on the right side. For example, a molecule that shows dextrorotation is turning or twisting to the right. The opposition of dextro- is levo- (from the Latin "laevus" meaning on the left side) so the opposite of dextrorotation is levorotation.


• dia-: Prefix taken straight from the Greek meaning through, throughout, completely as in diagnosis and dialysis.


• entero-: Combining form pointing to the intestine (the gut). "Entero-" comes from the Greek word "enteron" for intestine, related to the Greek "enteros" meaning "within." What went into the intestine was within the body.


• hetero-: Combining form from the Greek "heteros" meaning different. The opposite is homo- which comes from the Greek "homos" meaning same. For example, heterogeneous and homogeneous, heterosexual and homosexual, etc.
• homo-: Combining form from the Greek "homos" meaning "same." The opposite is hetero- from the Greek "heteros" meaning "different." For example, there is heterogeneous and homogeneous, heterosexual and homosexual, etc.


• hyper-: Means high, beyond, excessive, above normal. For example, hypercalcemia is high calcium in the blood and hypersensitivity is oversensitivity. The opposite of hyper- is hypo-.


• hypo-: Prefix meaning low, under, beneath, down, below normal. For example, hypocalcemia is low calcium in the blood and hyposensitivity is undersensitivity. The opposite of hypo- is hyper-.


• iatr-: Prefix relating to a physician or medicine. From the Greek word "iatros" meaning physician (healer). As in iatrogenic, generated by physicians, due to the activity of doctors.


• kerato-: Kerato- is a confusing since it can refer to the cornea (as in keratitis and keratocornea) or to "horny" tissue (as in keratin and keratosis).


• leuko-: Prefix meaning white from the Greek "leukos", white. As in leukocyte, a white cell (in the blood). Leuko- and leuco- are the same prefix, just different spellings. A leukocyte = a leucocyte. And leucemia = leukemia, a malignant disease of the white blood cells.


• levo-: From the Latin "laevus" meaning on the left side. For example, a molecule that shows levorotation is turning or twisting to the left. The opposition of levo- is dextro- (from the Latin "dexter" meaning on the right side) so the opposite of levorotation is dextrorotation.


• litho-: Prefix meaning stone. A lithotomy is an operation to remove a stone. Lithotripsy involves crushing a stone. The stone may be in the gallbladder or in the urinary tract.


• macro-: From the Greek "makros" meaning large or long. Terms with "macro-" include macrocyte (large cell), macroglossia (large tongue), macroscopic (visible with the naked eye), and macrosomia (big body). The opposite of "macro-" is "micro-."


• mega-: From the Greek "megas", great or big and means abnormally large. Megalocephaly is too large a head. Megacardia is too large a heart. Megacolon is too large a colon.


• melan-: Prefix meaning dark or black. It comes from the Greek "melas", black. Examples of terms containing melan- include melanin (dark pigment), melanocytes (cells that make melanin), and melanoma (a tumor arising in melanocytes).


• micro-: From the Greek "mikros" meaning small. Examples of terms involving micro- include microcephaly (small head), micropenis, microphallus, microscope, etc. The opposite of "micro-" is of "macro-."


• neo-: New. From the Greek "neos", new, young, fresh, recent. Examples of terms starting with "neo-" include neonatal and neonate (newborn), neoplasia and neoplasm (new growth = tumor), etc.


• oligo-: Means just a few, scanty. From the Greek "oligos" that likewise means few, scanty. Appears in oligodactyly (few fingers), oligohydramnios (too little amniotic fluid) and oligospermia (too few sperm).


• onycho-: Having to do with the nails. Medical terms involving "onycho-" include onychodystrophy (abnormal growth and development of nails), onychomycosis (fungal infection of the nails), and onychoosteodysplasia (malformation of bones and nails).


• osteo-: Combining form meaning bone. From the Greek "osteon", bone. Appears in osteoarthritis, osteogenesis (building of bone), osteomyelitis (inflammation of bone and marrow), osteopetrosis (stonelike bone), osteoporosis, osteosarcoma, etc.


• oto-: Combining form meaning ear. From the Greek "otos" pertaining to the ear. Appears for example in otitis (inflammation of the ear), otolaryngologist (an ENT doctor), otoscope (a device for looking in the ear), etc.


• patho-: Derived from the Greek "pathos" meaning "suffering or disease." Patho- serves as a prefix for many terms including pathogen (disease agent), pathogenesis (development of disease), pathology (study of disease), etc. The corresponding suffix is -pathy.


• phlebo-: Means vein. From the Greek "phleps", vein, which came from the root "phlein", to gush or overflow. Appears in phlebitis (inflammation of the veins), phlebotomist (a person who draws blood from veins), and phlebotomy (a venipuncture).


• pneumo-: Combining form pertaining to breathing, respiration, the lungs, pneumonia, or air. "Pneumo-" is derived from the Greek "pneuma" meaning wind, air, or breath. In French, a "pneu" is a tire (so called because it contains air).


• poly-: From the Greek "polys", many. The prefix "poly-" appears in many medical terms including polyarteritis, polycystic, polyp, etc. Poly is short for polymorphonuclear leukocyte (a type of white blood cell).


• pro-: A combining form (from both Greek and Latin) with many meanings including "before, in front of, preceding, on behalf of, in place of, and the same as." Used as a word, pro of course means professional and, in medicine, it is short for prothrombin.


• quasi-: Prefix meaning seemingly. As, for example, in quasidominant, seemingly dominant.


• toc-: From the Greek word "tokos" meaning childbirth, we have toc-, toco-, tok-, and toko- as combining forms, all referring to labor or childbirth. A tocolytic agent inhibits the uterine contractions.


• trans-: From the Latin meaning "across, over, or beyond." Medical terms containing "trans- " are many: transfusion, transplant, transurethral, transvaginal, etc.