How to Understand Medical Terminology

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This article will give you the fundamentals of understanding medical terms. You'll learn how medical words are derived from Latin, and usually will be constructed of a root word (foundation of the term) plus a prefix (word beginning) and/or suffix (word

It has been said that knowledge is power.  Gaining knowledge of one's own body and biological functions is indeed empowering.  This, in turn, can also aid in achieving better health through understanding, and hence we can become a proactive partner in our own health care.  Sometimes the medical terminology used when speaking of the body can be baffling and somewhat foreign to the lay person, and can deter the learning process.  This article is designed to introduce you to some of these terms, and help you learn how to understand them.  You may also find it helpful to read my related articles, Common Medical Abbreviations You Should Know and What Your Optical Prescription Means.

How to Understand Medical Terminology

The first step in understanding medical terminology is to understand how the words themselves are constructed.  Medical words are derived from Latin, and usually will be constructed of a root word (foundation of the term) plus a prefix (word beginning) and/or suffix (word ending) which give further information surrounding the root word.  For example, take the medical term electrocardiogram, also known as an ECG (or sometimes EKG).  It can be broken down like this:

electr/o = electricity

cardi/o = heart

gram = record

Just to clarify, the "o" in the above examples are vowels used to combine all the parts of the word ("electr" + "o" together is called a combining form; sometimes the "o" is dropped or changed to another vowel).  So, when we add up all the parts of this word, we see that an electrocardiogram literally translated means a record of the heart's electricity; to state it more clearly, it is a recording of electricity flowing through the heart.

The above example is a common medical term which many people already understand.   You may have heard other medical terms, but perhaps you're a little unsure as to the exact meaning.  Once you know a single root word, you'll be able to figure out more and more whole words which contain that root.  By learning the following list of root words, prefixes, and suffixes, you'll be well on your way to understanding most medical terminology that you are likely to encounter.  So as to point out their differences, note that I have included words or word parts that are similar to each other which often get confused. 

Root Words (Combining Forms) that form Common Medical Terms

Here you will find a root word, its meaning, and a medical term using this root.  The medical term includes a prefix or sufffix, which is indicated by Italics.  (The section below this contains the definition for these prefixes and suffixes.)

  1. andr/o = male; androgenic = produced by or in a male
  2. anter/o = front; anterior = pertains to the frontal side of the body or structure
  3. arthr/o = joint; arthroscopy = viewing the inside of a joint with a special scope
  4. ather/o = plaque, fatty substance; atherosclerosis = condition (hardening) of plaque (in this case, scler = hard and refers to the hardening of plaque buildup in the arteries)
  5. aur/o = ear; aural = of or relating to the ears
  6. bi/o = life; biopsy = microscopic examination of tissue, fluid or cells removed from a living body
  7. bil/i = bile, gall; bilirubinic = pertaining to bilirubin (bilirubin is a reddish-yellow pigment in bile and blood)
  8. blephar/o = eyelid; blepharoplasty = plastic surgery of the eyelid
  9. brachi/o = arm; brachial = pertaining to the arm
  10. bronch/o or bronchi/o = bronchial tube; bronchitis = inflammation of the bronchial tube(s)
  11. cardi/o = heart; pericardium = the membrane that surrounds the heart
  12. caus/o = burn; causalgia = burning pain
  13. cauter/o = heat, burn; cauterize = to burn
  14. cephal/o = head; cephalometry = the practice or science of measuring the head
  15. chem/o = drug; chemotherapy = treatment with drugs
  16. chondr/o = cartilage; chondroma = a cartilage-like mass (usually a benign tumor resmebling cartilage)
  17. chrom/o = color; chromatopsia = color vision
  18. chron/o = time; chronology = study of or through time; for medical purposes, tracking events over a specific period
  19. core/o = pupil; coreoplasty = surgery to change placement or size of pupil
  20. corne/o = cornea; corneal abrasion = abrasion of the cornea
  21. coron/o = heart; coronary artery = artery pertaining to the heart
  22. corpor/o = body; corporal = pertaining to the body
  23. crani/o = skull; cranium = structure of the skull
  24. dacry/o = tear; dacryocystitis = inflammation of a tear sac (Latin for sac = cyst)
  25. dactyl/o = finger, toes; dactylous = having (such) fingers or toes (usually associated with an anomaly)
  26. dent/i = tooth; dentist = literally, a tooth specialist
  27. derm/o = skin; epidermis = upper layer of skin
  28. dist/o = far, distant; distal  = pertains to being distant, or far from the point of origin or attachment 
  29. dors/o = back (of body); dorsal = pertains to the back, or posterior
  30. duct/o = to lead or carry; abduction = process of drawing away from
  31. electr/o = electricity; electrolysis = destruction of (hair roots) using an electric current
  32. encephal/o = brain; encephalitis = inflammation of the brain
  33. enter/o = intestines (usually pertains to small intestines); enteric = of or relating to the intestines; this generally refers to a medication that is designed to pass through the stomach unaltered directly to the intestines, such as enteric aspirin
  34. estr/o = female; estrogen = produced by or in a female (to be exact, estrogen is a female sex hormone)
  35. gastr/o = stomach; gastrotomy = surgical incision into the stomach 
  36. gest/o = pregnancy; gestosis = any disorder of pregnancy (but usually associated with toxemia)  
  37. gluc/o or glyc/o = glucose, sugar; hypoglycemia = low blood sugar
  38. gnos/o = knowledge; prognosis = literal translation means pertaining to pre-knowledge (pro=before, or pre); more specifically, a prognosis is the act of foretelling the course of a disease.
  39. hem/o or hemat/o = blood; hematoma = mass of blood, usually clotted and accumulated in a tissue, organ, or cavity
  40. hepat/o = liver; hepatitis = disease or condition marked by inflammation of the liver
  41. hist/o or histi/o = tissue; histoid = resembling tissue - refers to tumors which resemble normal tissue
  42. home/o = sameness; homeostatis = maintaining a relatively stable internal physiological condition (eg. body temperature) under fluctuating external conditions. (statis = control)
  43. hydr/o = water; hydrotherapy = treatment using water 
  44. idi/o = unknown; individual, distinct; idiopathic = disease or condition arrising from an unkown or obscure cause 
  45. kines/o or kinesi/o = movement; kinesiology = the study of movement, as applies to the principles of mechanics and anatomy in humans 
  46. later/o = side; lateral = pertains to the side (location or movement)
  47. leth/o = death; lethal = causing death
  48. leuk/o = white; leukocyte = white blood cell
  49. lingu/o = tongue; lingual = of or relating to the tongue
  50. lip/o = fat; lipid; liposuction = removal of excess fat by means of suction
  51. mi/o = smaller; miotic = pertaining to being smaller; refers to pupils that are abnormally small
  52. my/o = muscle; myalgia = muscle pain
  53. myel/o = spinal cord, marrow; myelodysplasia = abnormal development of the spinal cord, sometimes known as preleukemia
  54. neur/o = nerve; neuropathy = diseased nerves (leads to loss of sensation and eventual death of tissue)
  55. phak/o = lens of eye; aphakic = having no lens in the eye
  56. plas/o = development, formation; neoplastic = new growth
  57. presby/o = old age; presbyopia = literally translated means old eyes; refers to the normal decline in near vision as a person reaches the age of 40 or older
  58. rhin/o = nose; rhinoplasty = plastic surgery to reform the nose
  59. scot/o = darkness; scotoma = a mass of darkness; refers to a blind spot in one's vision associated with a disease or abnormal condition (often encountered in both glaucoma and macular degeneration)
  60. xer/o = dry; xeroderma = dry skin

Prefixes used in Medical Terminology

  1. a-, an- = not, without (asymptomatic refers to a condition or disease in which the patient is not experiencing any symptoms)
  2. ab- = away from
  3. ad- = toward
  4. ante- = before, preceding (as in anterior)
  5. anti- = against (as in antivirus)
  6. bi- = two (do not confuse with bi/o, a root word meaning life)
  7. con- = with, together
  8. contra- = against (as in contraindication, which usually refers to a drug or treatment that cannot be used safely with another drug or treatment)
  9. de- = down, lack of
  10. dia- = complete, through
  11. dorsi- = back
  12. dys- = bad, painful, abormal
  13. ec-; ecto- = outside (as in ectopic pregnancy, where a fetus begins growing outside the uterus)
  14. em-; en- = in, within
  15. epi- = above, on
  16. eu- = good (as in euphoria)
  17. ex-; exo- = out, away from
  18. hemi- = half
  19. hyper- = above, excessive, more (hyperthyroidism is a condition where the thyroid gland is over active; hypothyroidism is when the thyroid gland is under active)
  20. hypo- = low, less, deficient, under
  21. infra = below, beneat
  22. inter = between
  23. intra = within
  24. mal- = bad (as in malignant tumor)
  25. meta- = change
  26. neo- = new
  27. peri- = surrounding (as in pericardium, the membrane surrounding the heart)
  28. tachy- = fast (as in tachycardia, a condition of the heart beating much too fast)

Suffixes used in Medical Terminology

  1. -ac, -al, -ar = pertaining to
  2. -algia = pain
  3. -cyte = cell
  4. -ectomy = excision, removal
  5. -emia = blood condition (sometimes used as a combining form with a prefix, as in anemia, meaning blood deficiency)
  6. -genic = pertaining to, producing, produced by, or produced in
  7. -gram/graph = record/intstrument for recording
  8. -ic, -ical = pertaining to
  9. -ion = process
  10. -ist = specialist in
  11. -itis = inflamation
  12. -lysis = breakdown, separation, or destruction
  13. -meter, -metry = measure, measurement
  14. -oid = resembling
  15. -ology = study of
  16. -oma = tumor, mass, swelling
  17. -opsy = to see, viewing; examine with microscope (usually of tissue removed from body)
  18. -osis, esis = condition, usually abnormal 
  19. -plasty = surgical repair; formation
  20. -pathy = diseased condition
  21. -scope = instrument used to visually examine
  22. -sis = condition, usually abnormal
  23. -tomy = incision, process of cutting
  24. -um = structure, tissue, thing
  25. -y = process, condition

So, you can see how understanding root words, prefixes and suffixes can lead to a better understanding of medical terminology.  This, in turn, can indeed empower us to understand more of our own bodies, and of diseases, laboratory tests, and medical procedures. 


That is quite a list of medical terms and abbreviations, and there is no need to memorize this, but you will have it handy when and if you need to look something up. As we progress through the 21st century, there are more and more medical discoveries, medical studies and results, which means more and more abbreviations and acronyms.

If your doctor uses a term, abbreviation or acronym when talking with you, never feel too skittish, foolish or embarrassed to ask your doctor exactly what he or she is talking about. And if you still don’t understand, ask for a clarification. Too many times a doctor will make us feel dumb or talk down to us, never ever feel that way and make them explain to you exactly what they are telling you.

© Sharla Smith, February 2012

Image Credit: courtesy Egilshay on Stock.xchng


My own knowledge from training in Medical Terminology Courses, supported by the following texts:

The Language of Medicine; Davi-Ellen Chabner; Saunders, 2004

Mirriam-Webster's Medical Dictionary; Merriam-Webster Incorporated, 2006


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