- Identify word parts in medical terms.
- Examine the rules for building medical terms.
Word Parts
Medical terms are built from word parts. Those word parts are , , , and . When a word root is combined with a combining form vowel the word part is referred to as a .
Identifying Word Parts in Medical Terms
By the end of this book, you will have identified hundreds of word parts within medical terms. Let’s start with some common medical terms that many non-medically trained people may be familiar with.
Osteoarthritis
Oste/o/arthr/itis – Inflammation of bone and joint.
Oste/o is a that means bone
arthr/o is a that means joint
-itis is a that means inflammation
Intravenous
Intra/ven/ous – Pertaining to within a vein.
Intra- is a that means within
ven/o – is a that means vein
-ous is a that means pertaining to
Notice, when breaking down words that you place slashes between word parts and a slash on each side of a .
Language Review
Before we begin analyzing the rules let’s complete a short language review that will assist with pronunciation and spelling.
Short Vowels
a, e, i, o, u, and sometimes y are indicated by lower case.
Long Vowels
A, E, I, O, U are indicated by upper case.
Consonants
Consonants are all of the other letters in the alphabet. b, c, d, f, g, h, j, k, l, m, n, p, q, r, s, t, v, w, x, and z.
Language Rules
Language rules are a good place to start when building a medical terminology foundation. Many medical terms are built from word parts and can be translated . At first, literal translations sound awkward. Once you build a medical vocabulary and become proficient at using it, the awkwardness will slip away. For example, suffixes will no longer be stated and will be assumed. The definition of intravenous then becomes within the vein.
Since you are at the beginning of building your medical terminology foundation, stay literal when applicable. It should be noted that as with all language rules there are always exceptions and we refer to those as .
Language Rules for Building Medical Terms
- When combining two , you keep the .
- When combining a with a that begins with a consonant,
you keep the .
Gastr/o/enter/o/logy – The study of the stomach and the intestines
- Following rule 1, when we join combining form gastr/o (meaning stomach) with the combining form enter/o (meaning intestines) we keep the combining form vowel o.
- Following rule 2, when we join the combining form enter/o (meaning intestines) with the suffix -logy (that starts with a suffix and means the study of) we keep the combining form vowel o.
- When combining a with a that begins with a vowel, you drop the .
- A goes at the beginning of the word and no is used.
Intra/ven/ous – Pertaining to within the vein
- Following rule 3, notice that when combining the combining form ven/o (meaning vein) with the suffix -ous ( that starts with a vowel and means pertaining to) we drop the combining form vowel o.
- Following rule 4, the prefix intra- (meaning within) is at the beginning of the medical term with no combining form vowel used.
- When defining a medical word, start with the first and then work left to right stating the word parts. You may need to add words. As long as the filler word does not change the meaning of the word you may use it for the purpose of building a medical vocabulary. Once you start to apply the word in the context of a sentence it will be easier to decide which filler word(s) to
choose.
Intra/ven/ous – Pertaining to within the vein or Pertaining to within a vein.
- Following rule 5, notice that I start with the suffix -ous (that means pertaining to) then we work left to right starting with the prefix Intra- (meaning within) and the combining form ven/o (meaning vein).
- Notice that we have used two different definitions that mean the same thing.
- In these examples we do not have the context of a full sentence. For the purpose of building a medical terminology foundation either definition is accepted.
Medical terminology is language used to describe anatomical structures, processes, conditions, medical procedures, and treatments. At first glance, medical terms may appear intimidating, but once you understand the basic word structure and the definitions of some common word elements, the meaning of thousands of medical terms can be easily parsed.
Most medical terms adhere to a fixed structure of a prefix, root, and suffix. These word components are assembled like building blocks to create a vast vocabulary.
Greeks are considered the founders of rational medicine and medical terms are primarily derived from Greek and Latin.1 Over centuries, the language of medicine has evolved into multiple national medical languages. Today, medical English is the dominant language for international communication. English is used in most influential medical journals and it has become the language of choice at international conferences.2
Basic Term Structure
Medical terms are comprised of these standard word parts:
- Prefix: When included, the prefix appears at the beginning of a medical term and usually indicates a location, direction, type, quality, or quantity.
- Root: The root gives a term its essential meaning. Nearly all medical terms contain at least one root. When a prefix is absent, the term begins with a root.
- Suffix: The suffix appears at the end of a term and may indicate a specialty, test, procedure, function, disorder, or status. Otherwise, it may simply define whether the word is a noun, verb, or adjective.
- Combining vowel: A combining vowel (usually the letter “o”) may be added between word parts to aid in pronunciation.
Breaking a word down into its component parts should help readers determine the meaning of an unfamiliar term. For example, hypothermia has the prefix hypo- (meaning below normal), the root therm (heat or warmth), and the suffix -ia (condition).
Word Roots
A root is the foundational element of any medical term. Roots often indicate a body part or system.
Common word roots:
brain | enceph |
ear | ot, aur |
eardrum | tympan, myring |
eye | ophthalm, ocul |
face | faci |
nose | rhin |
skull | crani |
tongue | lingu |
tooth | odont, dent |
aorta | aort |
arteries | arteri |
blood | hem, sangu |
blood vessels | angi |
heart | cardi |
veins | ven, phleb |
arm | brachi |
back | dorsa |
bone | oste |
foot | pod, ped |
muscle | myo |
rib | cost |
shoulder | scapul |
wrist | carp |
appendix | append |
colon | col |
esophagus | esophag |
intestine (usually small) | enter |
kidney | ren, neph |
liver | hepat |
stomach | gastr |
cancer | carci |
drug | chem |
electric | electr |
heat | therm |
knowledge | gnos |
life | bi |
pressure | bar |
returned sound | echo |
Compound Words
A medical word may include multiple roots. This frequently occurs when referencing more than one body part or system. For example, cardio-pulmo-nary means pertaining to the heart and lungs; gastro-entero-logy means the study of the stomach and intestines.
Combining Forms
A combining vowel is used when a root is followed by another word part that begins with a consonant. A combining vowel (usually the letter ‘o’) is added after the root (e.g. neur-o-logy) to aid pronunciation. The root and vowel together (e.g. neur-o) are called the combining form. For simplicity, combining vowel options are omitted from the word part tables.
Prefixes
A prefix modifies the meaning of the word root. It may indicate a location, type, quality, body category, or quantity. The prefix is optional and does not appear in all medical terms.
Common prefixes:
large | macro-, mega(lo)- |
small | micro- |
half | semi- |
half (one side) | hemi- |
one | mono-, uni- |
two | three | four | bi- | tri- | quad(ri)- |
equal | equi- |
many | poly- |
above normal | hyper- |
below normal | hypo- |
normal/good | eu- |
before | pro-, pre-, ante- |
after | post- |
back/backward | retro- |
again | re- |
fast | tachy- |
slow | brady- |
new | neo- |
time, long time | chron- |
away from | ab- |
above | supra- |
around | peri- |
across | trans- |
between | inter- |
out of, outside | ex-, ec(t)- |
self | auto- |
through, completely | dia- |
together | con- |
toward | ad- |
within, inside | end(o)- |
against | anti-, contra- |
bad | mal- |
cause | eti- |
self | auto- |
without | a-, de- |
abnormal, bad | dys- |
Suffixes
Medical terms always end with a suffix.3 The suffix usually indicates a specialty, test, procedure, function, condition/disorder, or status. For example, “itis” means inflammation and “ectomy” means removal.
Alternatively, the suffix may simply make the word a noun or adjective. For example, the endings -a, -e, -um, and -us are commonly used to create a singular noun (e.g. crani-um).
Though the suffix appears at the end of the term, it often comes first in the definition. For example, appendicitis means inflammation (-itis) of the appendix.4 Accordingly, it is sometimes helpful to read unfamiliar medical terms from right to left.
Occasionally, a medical term may be comprised of a prefix and suffix. For example, apnea includes the prefix a- (without) and suffix -pnea (breathing).
Common suffixes (letters in parenthesis are not always present):
(noun form) | -a, -e, -um, -is |
causing | -genic |
condition | -ia, -ism, -sis, -y |
specialty | -iatry, -iatrics, -ics |
specialist | -ian, -ist |
structure | -um, -us |
small, little | -ula, -ulum, -ulus |
study of | -logy |
pertaining to | -ac, -ar(y), -(e/i)al, -ic(al), -ior, -ory,, -ous, -tic |
removal of | -ectomy |
image/record | -gram |
recording instrument | -graph(y) |
cut in | -otomy |
visual examination | -scopy |
opening | -stomy |
blood (condition of) | -emia |
breathing | -pnea |
inflammation | -itis |
condition or disease | -osis |
deficiency | -penia |
disease | -pathy |
excessive flow | -rrhag(e/ia) |
mass, tumor | -oma |
Plural Forms
Adding an “s” or “es” to the end of a word is often the straightforward method to make a word plural in English and many modern Romance languages. In medical terminology, however, things are a little more complicated. The plural form of each word is based on the last two letters of the singular suffix.
There are several exceptions. For example, “virus” is a Latin term without a plural form. “Viruses” is the accepted plural form. Elsewhere, the suffix “s” or “es” has occasionally prevailed in common usage. For example, the plural form of “hematoma” is “hematomas” rather than “hematomata.”
Common singular endings and corresponding plural endings:
Singular | Plural |
a | ae |
en | ina |
ex, ix, yx | ices |
is | es |
ma | mata |
(a/i/y)nx | nges |
um | a |
us | i(i) |
Additional resources:
- OpenMD Medical Dictionary and word parts glossary, which provides definitions for 750 medical roots, prefixes, and suffixes.
- Understanding Medical Words by MedlinePlus provides a concise introduction to medical terminology and several quizzes.
- TheFreeDictionary's Medical Dictionary by Farlex is a comprehensive dictionary of medical terms (including word parts) from American Heritage, Collins Encyclopedia, and other major publishers.
References
- Banay, G L. “An Introduction to Medical Terminology I. Greek and Latin Derivations.” Bulletin of the Medical Library Association vol. 36, 1 (1948).
- Wulff, Henrik R. “The language of medicine.” Journal of the Royal Society of Medicine vol. 97,4 (2004): 187-8.
- Ehrlich, Ann; Schroeder, Carol L. Introduction to Medical Terminology. Centage Learning, 2015.
- Nath, Judi Lindsley; Lindsley, Kelsey P. A Short Course in Medical Terminology. Wolters Kluwer Health, 2018.
- Cohen, Barbara J. Medical Terminology: An Illustrated Guide. 6th ed. Baltimore, MD: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2011. Table 2-4.
Published: January 9, 2020
Last updated: December 24, 2021