/ Thesaurus / E Synonyms of extension courses Find synonyms for: Noun1. extension course, course, course of study, course of instruction, classusage: a course offered as part of an extension serviceWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: leonine Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language