1.2 Basic Word Structure

Word Parts

Medical terms are built from word parts, which are also called component parts. These parts are prefix, word root, suffix, and combining form vowel. When a word root is put together with a combining form vowel, the word part is referred to as a combining form.

Below you will see definitions of the component parts of medical terms. Throughout this chapter, and the book as a whole, you will learn many different examples of these word parts and apply that knowledge through the activities provided.


Key Concept

  • A prefix goes at the front of the term and changes the meaning.
    • Example: dys– means “bad,” “painful,” “difficult,” or “abnormal”
    • Notice that a prefix always has a  “-” after it when not in a medical term. This lets you know that the prefix needs something after it. Not all medical terms have a prefix.
  • A suffix goes at the end of the term and changes the meaning.
    • Example: logy means “study of”
    • Notice that a suffix always has a “-” before it when not in a medical term. This lets you know that the suffix needs something before it. All medical terms have a suffix.
  • The root gives the essential meaning of the term.
    • Example: cardi means “heart”
    • A medical term may have one or more roots. In some rare cases, a term may not have a root because the root is embedded in the suffix.
  • A combining vowel has no meaning but connects roots to suffixes and roots to other roots.
    • A combining vowel is almost always an o, but in some rare cases, it is an i.
  • A combining form is the combination of the root and the combining vowel.
    • Example: Combining the root cardi with a combining vowel creates cardi/o.


Once you become more familiar with all the common word parts, you will be able to use this knowledge to break down any medical term into its component parts and determine its meaning. Although you have just started learning medical terminology, the example below demonstrates how a medical term can be broken apart so you can understand its meaning.



The medical term, pericardium can be broken into the following  components parts:


The prefix peri- means “surrounding,” the root cardi means “heart,” and -um is a suffix that means “structure.” If you put it all together, the term pericardium means “a structure surrounding the heart.”







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



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The Language of Medical Terminology Copyright © 2022 by Lisa Sturdy and Susanne Erickson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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