Entry 1 sense Webster, 1913 Conjectural · Con·jec·tur·al · IPA 01 a. Dependent on conjecture; fancied; imagined; guessed at; undetermined; doubtful. 1. Dependent on conjecture; fancied; imagined; guessed at; undetermined; doubtful. “And mak'st conjectural fears to come into me.” — Shak. “A slight expense of conjectural analogy.” — Hugh Miller. “Who or what such editor may be, must remain conjectural.” — Carlyle.