/ Thesaurus / S Synonyms of semimajor axis Find synonyms for: Noun1. semimajor axis, axisusage: one-half the major axis of an ellipse; the distance from the center of an ellipse to one endWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: languid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language