To form, without certain knowledge, but from probable indications, a notion concerning; form a provisional or an imperfect opinion concerning; conjecture; surmise.To conjecture rightly; solve by a correct conjecture; form a true opinion of: as, to guess one's design; to guess a riddle.In a loose use, to believe; think; suppose; imagine: with a clause for object.[This use is common in English literature from the first appearance of the word; but it is now regarded as colloquial, and, from its frequency in the United States, it is generally supposed by Englishmen to be an “Americanism.” By an easy extension guess is used for think, believe, or suppose, even where the meaning is not at all conjectural, but positive, and it is then logically superfluous, serving merely to make the assertion less abrupt: as, I guess I will go now (that is, I am going now); I guess I know what I'm about (that is, I know what I am doing). In most instances this use probably arises from a desire to avoid positive assertion, or from some feeling of hesitation or uncertainty.] Synonyms Imagine, Presume, etc. See conjecture.To form a conjecture; judge or conclude from incomplete or uncertain evidence: commonly with at or by.n. A notion gathered from mere probability or imperfect information; a judgment or conclusion without sufficient or determinate evidence; a conjecture; a surmise: as, to act by guess.n. See another-guess, a.