/ Thesaurus / D Synonyms of diagnostic assay Find synonyms for: Noun1. diagnostic test, diagnostic assay, assayusage: an assay conducted for diagnostic purposesWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: reclusive Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language