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 in order 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 you become more proficient at using medical terminology, the initial awkwardness will disappear. For example, suffixes will no longer be stated and will be assumed, like the literal definition of intravenous, which is “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.
Rule 1: When joining two combining forms, keep the combining form vowel.
Rule 2: When joining a combining form with a suffix that begins with a consonant, keep the combining form vowel.
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 “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 (which starts with a consonant and means “the study of”), we keep the combining form vowel o.
Rule 3: When joining a combining form with a suffix that begins with a vowel, drop the combining form vowel.
Rule 4: A prefix goes at the beginning of the word, and no combining form vowel 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 (which 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.
Rule 5: When defining a medical word, start with the suffix (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. 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.
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”).
- 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 of intravenous is acceptable.
Unless otherwise indicated, material on this page has been adapted from the following resource:
Carter, K., & Rutherford, M. (2020). Building a medical terminology foundation. eCampusOntario. https://ecampusontario.pressbooks.pub/medicalterminology/ licensed under CC BY 4.0