Medical Terms - Explaining The Terminology

Get to know medical terms.

The Foremost of Medical Building Blocks...Prefixes

The language of medicine may sometimes seem like gobbledygook, a wordy and generally unintelligible jargon. Indeed, one of the barriers sometimes separating medical people from the rest of the world is language. Medical people - doctors, nurses, and others in the health professions - use a lingo with special words. And these words, whether by design or not, are often incomprehensible to the rest of us.

Medical terms are often compound words. They are put together from other words that serve as the building blocks of medical language. The gobbledygook of medicine can often be understood if we can but recognize and glean the meaning of the individual building blocks. Take the word "pericardial." It is the sum of its parts, from the Greek: "peri-", around + "kardia", heart = around the heart.

Among the key building blocks in medical language (and all language) are the prefixes, the parts we affix to the front of words. Examples of prefixes that appear in the MedicineNet Medical Dictionary ( include:

  • a- and an-: The single letter "a-" is much employed in the health sciences. It indicates "not, without, -less." So, for example, we have alexia (not reading), aphagia (not eating), aphonia (not voice, voiceless). The prefix "a-" comes from the Greek meaning "not." It becomes "an-" before a vowel, as in anemia (no blood), anotia (no ear), and anoxia (no oxygen).
  • ab- and ad-: "Ab-" means "from, away from, off." In medicine, abduction is the movement of a limb away from the midline of the body. "Ad-" is just the opposite of "ab-". It means "toward" and "in the direction of" (among other things). Adduction is movement of a limb toward the midline of the body.
  • alb-: "Albus" is the color white in Latin. 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-: From the Greek "kolpos" meaning a fold, cleft, or hollow. Used in reference to the vagina. Words incorporating colpo- include colposcopy (examination of the vagina and cervix with a colposcope).
  • entero-: From the Greek "enteron", intestine. Related to the root "enteros" meaning "within." What went into the intestine was within the body. Enteritis is inflammation of the intestine.
  • kerato-: Confusing since it can refer to the cornea (as in keratitis, inflammation of the cornea) or to "horny" tissue (as in keratosis, thickening of the skin).
  • litho-: Prefix meaning stone ("lithos" in Greek = 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.
  • melan-: From the Greek "melas", black. Terms containing melan- include melanin (dark pigment), melanocytes (cells that make melanin), and melanoma (a tumor arising in melanocytes).
  • neo-: New. From the Greek "neos", new, young, fresh, recent. There is the neonatal (newborn) intensive care unit. A neoplasm is a new growth, a tumor.
  • oligo-: Means just a few, scanty. In oligodactyly (too few fingers), oligohydramnios (too little amniotic fluid) and oligospermia (too few sperm0.
  • onycho-: Has to do with the nails. In onychodystrophy (abnormal development of nails)and onychomycosis (fungal infection of the nails).
  • osteo-: Bone. In osteoarthritis, osteopetrosis (stonelike bone), osteoporosis, etc.
  • oto-: The ear. In otitis (inflammation of the ear), otolaryngologist (an ENT doctor), otoscope (a device for looking in the ear), etc.
  • patho-: From the Greek "pathos" meaning "suffering or disease." In pathogen (disease agent), pathogenesis (development of disease), pathology (study of disease), etc.
  • phlebo-: Means vein. In phlebitis (inflammation of the veins), phlebotomist (a person who draws blood from veins), and phlebotomy (a venapuncture).
  • pneumo-: Pertaining to breathing, respiration, the lungs, or air. In pneumonia, pneumothoxax, etc. In French, a "pneu" is a tire (because it contains air).
  • poly-: Many. Poly-appears in many medical terms including polyarteritis, polycystic, polyp, etc.
  • toc-: From the Greek word "tokos", refers to labor or childbirth. A tocolytic agent inhibits uterine contractions and decreases or stops labor.
  • xero-: From the Greek "xeros", dry or parched. If the doctor says you have xeroderma, you just have dry skin.

These and other prefixes are explained along with many other medical terms at



  1. MedicineNet


Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care August 1, 2017

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