1.3 Medical Language Rules
Language Rules for Building Medical Terms
There are a few rules that should be followed when interpreting and writing medical terms. It is important to memorize these rules to prevent errors. It is also important to note that with any language, there are always exceptions to the rules. Once you start to build a medical vocabulary and become proficient at using it, understanding medical terminology will become much easier.
Since you are at the beginning of building your medical terminology knowledge base, it is best to be literal when learning medical terms. Later, when using medical terminology becomes more familiar to you, the initial awkwardness will disappear. For example, suffixes will no longer be stated and will be assumed, like the literal definition of intravenous, which means “pertaining to within the vein.” As you become more familiar with medical terminology, you will read this as “within the vein.” So let’s begin by learning the language rules for medical terminology.
Language Rules
Rule 1: When joining two roots or combining forms, keep the combining vowel.
Rule 2: When joining a combining form with a suffix that begins with a consonant, keep the combining vowel.
Example
gastr/o/enter/o/logy – “the study of the stomach and intestines”
- Following Rule 1, when we join the combining form gastr/o (meaning “stomach”) with the combining form enter/o (meaning “small intestine”), we keep the combining vowel o between the two roots.
- Following Rule 2, when we join the combining form enter/o (meaning “small intestine”) with the suffix -logy (which starts with a consonant and means “the study of”), we keep the combining vowel o.
Rule 3: When joining a combining form with a suffix that begins with a vowel, drop the combining vowel.
Rule 4: A prefix goes at the beginning of the word, and no combining vowel is used between the prefix and the combining form.
Example
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 (which starts with a vowel and means “pertaining to”), we drop the combining vowel o.
- Following Rule 4, the prefix intra- (meaning “within”) is at the beginning of the medical term with no combining vowel used.
Rule 5: When defining a medical word, start with the suffix (at the end of the term), then work from left (the start of the term) to right, stating the word parts. You may need to add filler words to complete the definition. As long as the filler word does not change the meaning of the term, 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.
Example
intra/ven/ous – “pertaining to within the vein” or “pertaining to within a vein”
- Following Rule 5, start with the suffix -ous (meaning “pertaining to”), then work from left to right starting with the prefix intra- (meaning “within”) and the combining form ven/o (meaning “vein”).
- In these examples, we do not have the context of a full sentence, so we have used the articles “the” and “a” in front of the word “vein.” Those articles can be classified as filler words, as discussed in Rule 5. For the purpose of building a medical terminology foundation, either definition of intravenous is acceptable.
Exercises
Attribution
Unless otherwise indicated, material on this page has been adapted from the following resources:
Sturdy, L., & Erickson, S. (2022). The language of medical terminology. Open Education Alberta. https://pressbooks.openeducationalberta.ca/medicalterminology/, licensed under CC BY-NC-SA 4.0
