Most medical terms can be broken down into one or more word parts. There are a total of four different word parts, and any given medical term may contain one, some, or all of these parts. We will classify these word parts as: (1) roots, (2) prefixes, (3) suffixes, and (4) linking or combining vowels. An example of a word with three parts is the medical term "pericarditis," which means "inflammation of the outer layer of the heart." Pericarditis can be divided into three parts:
peri - card - itis
Once divided into parts, pericarditis can be translated: the prefix "peri" translates to "surrounding," the root "card" translates to "heart," and the suffix "itis" translates to "inflammation." Hence, pericarditis is an inflammation of the area surrounding the heart, or an inflammation of the outer layer of the heart, anatomically known as the pericardium [go to Mayo Clinic's Pericarditis page].
Medical terms always consist of at least one "root," although they may contain more—sometimes several more. The root of a word is that part which contains the essential meaning of the word. An example of this was seen above in the term "pericarditis." The root of the word – card – refers to the heart, so any prefix or suffix added to the root (card) will only function to add to the specificity of that word. An example of this would be the prefix "brady," which means "slow." If "brady" is added to the root "card," the term "bradycard" – which roughly means "slow heart" – is created. Then, if the suffix "ia" – which means "a condition or state" – is added to "bradycard," the medical term "bradycardia" is formed. The translation of bradycardia (brady - card - ia) is slow - heart - state, or the condition of a slow heart rate.
As was discussed above, a medical term must have at least one root, but does not have to have a prefix and/or a suffix. An example of this is the term "sternocleidomastoid," which is a muscle that has attachments at the sternum, the clavicle, and the mastoid. The term sternocleidomastoid can be divided into three parts (three roots, in this case): stern - o - cleid - o - mastoid. Notice that there are vowels between the three roots. These are "linking or combining vowels," which serve to make a term easier to pronounce. The vowel used most of the time is "o," but other vowels such as "i" and "a" are also used. Combining vowels are often used between roots and suffixes or roots and other roots, but they are not used between prefixes and roots.