Breadcrumb Home > Thesaurus > O Synonyms of ornithine Find synonyms for: Noun1. ornithine, amino acid, aminoalkanoic acidusage: an amino acid that does not occur in proteins but is important in the formation of ureaWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of ornithine (Dictionary) ✖ Related Content Daily Word Quiz: rococo Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language