/ Thesaurus / E Synonyms of essential amino acid Find synonyms for: Noun1. essential amino acid, amino acid, aminoalkanoic acidusage: an amino acid that is required by animals but that they cannot synthesize; must be supplied in the dietWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: loathe Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language