SEER Training Modules

Word Roots

Medical terms can be divided into three basic word elements: prefixes, roots (or stems), and suffixes. The root or stem of a medical term usually has been derived from a Greek or Latin noun or verb. This root expresses the basic meaning of the term. However, often that meaning will be modified by the addition of a prefix (at the beginning of the word) or the addition of a suffix (at the end of the word). Frequently a root + a suffix will be used as a suffix and added to another root as a word ending. Some examples are -emia, -genic, -penia, and -pathy. However, two suffixes alone cannot combine to form a word. Three common medical terms, their roots, and their root definitions are listed below.

Medical Term Root Root Definition
tonsillitis tonsilla tonsil (Latin tonsilla)
thermal therm heat
prognosis gno to know

Click here for an exercise on word roots.