Synonyms for SURMISE: guess, conjecture, theory, guessing, hypothesis, supposition, hunch, speculation; Antonyms of SURMISE: prove, establish, demonstrate, determine, learn, ascertain, document, validate, These are words and phrases related to surmise. Click on any word or phrase to go to its thesaurus page. Or, go to the definition of surmise. From the expression on his face, she surmised that something bad had happened. Guess who called yesterday? They estimate that the work will take at least ten weeks., Synonyms for Surmise (other words and phrases for Surmise)., Synonyms for SURMISE: guess, conjecture, imagine, presume, speculate, suppose, guess, assumption, conjecture, presumption, …, Synonyms for SURMISE: conjecture, guess, opinion, infer, suppose, assumption, attempt, believe, conclude, conclusion, deduce, deduction; Antonyms for SURMISE: knowledge, measurement, calculation, question, wonder., Find all the synonyms and alternative words for surmise at Synonyms.com, the largest free online thesaurus, antonyms, definitions and translations resource on the web..