How are Medical Terms Put Together? Just Like a Train!

Most medical terms consist of one or more parts. These word parts may include one or more of the following:

Image of Steam Engine representing a Prefix which are word parts attached to the beginning of root words. Photo courtesy Dr. Jim Brown

Prefixes - Prefixes are the word parts attached to the beginning of the root word. With some exceptions, the most common ones used in medical terminology can be divided into four broad categories that express (1) quantity, (2) position or time, (3) visual appearance in shape, size, and color, and (4) condition. The simplest of these categories are those expressing quantity. Again, the prefix is like the engine in a train. It is connected right up front and based on its characteristics you can almost guess what the rest of the train will look like.

Image of a box car representing a root word which is the main part or foundation of the word. Photo courtesy Dr. Jim Brown

Root Words - The word root is the main part, or foundation, of the word; it contains the word's essential meaning. Word roots often indicate a body part. As mentioned before, the root words are like the box cars in the freight train. They carry the actual freight which is the purpose for the train. The money that a particular train earns for the railroad is based upon what freight the train in carrying. The box cars are like the root words in that they represent the most important part of the train from a dollars and cents point of view.

Image of a caboose representing a sufflix which like the caboose is found at the end of a word and modifies the words meaning. Photo courtesy Dr. Jim Brown

Suffixes - The suffix is the word ending. Attaching a suffix to the end of a word modifies the word's meaning. Suffixes frequently indicate a procedure, a condition, or a disease. The caboose, like the sufflix, signifies "the end" of the train. The caboose modifies the train's "meaning" in that it identified which railroad company was actually running the train. A bright red Jersey Central Lines caboose with its distinctive Statue of Liberty symbol told everyone that train was run by Jersey Central. Suffixes similarly are easily identified and immediately indicate a procedure, condition or disease.

Image of a freight train gondola car which represents a combining vowel. Photo courtesy Dr. Jim Brown

Combining Vowels - Combining vowels or connecting vowels are sometimes used to create a more fluid transition between word parts and to make medical terms easier to pronounce. The vowel used most often to combine medical words is "O", but other vowels are also sometimes used. It should be noted that combining vowels may be used between two root words, or between a root word and a suffix, but they are never used between prefixes and root words. I always thought of the combining vowels as the flat cars or gondola cars on a train. They were frequently empty and just served to connect two box cars together. Combining vowels frequently just connect two root words or a root word and a suffix together.

Combining Forms - is simply the root word plus the combining vowel. For example "Hemat" is the root word meaning blood. "O" is the combining vowel. "Hemat-o" would be the combining form.

To help you better understand how this works, let's look at an example.

Consider the word cholecystectomy.

At first glance, this word seems quite complex. Cholecystectomy, which means excision (removal) of the gall bladder, is really a combination of four different word parts. Let's break it down into its sub parts and see if we can figure out why it means what it means.

chol - e - cyst - ectomy

chol is a root word meaning bile or gall
e is a combining vowel (described in more detail below)
cyst is another root word meaning bladder
ectomy is a suffix which translates to excision or surgical removal.

Therefore, we can see that cholecystectomy is a combination of words which translate to mean surgical removal of the gall bladder.

Hear the correct pronunciation in English or Spanish.

Each of these word parts will be seen over and over in medical language. For example, the suffix ectomy is seen in such common terms as tonsillectomy (removal of the tonsils) and appendectomy (removal of the appendix). It is not hard to see that as you begin to commit these sub-terms to memory, you will be able to decipher more complex terms because you will recognize and understand their component parts.

Open cholecystectomy: fundus down dissection. Open cholecystectomy. In so-called fundus down dissection, the fundus and infundibulum are retracted up and away from the liver while dissection is performed with electrocautery. Sharp dissection with scissors or scalpel or blunt digital dissection all may be used, at the surgeon's discretion. Image courtesy Medscape
A cholecystectomy being performed by a surgeon

Medical terms always contain at least one root word. And as we saw with cholecystectomy, they may have more than one root word. The root is the part of the word that comprises the primary meaning of the term. In the example of tonsillectomy, the root word is tonsil. The suffix is ectomy. The root word tonsil is capable of standing alone. The suffix ectomy, (meaning surgical removal) requires the root word tonsil to confer relevance. Prefixes and suffixes cannot stand alone. Medical terms may have, but are not required to have, a prefix and/or a suffix.