conjectural adjective 1noun 1forms 3 adjective1 •In the nature of a conjecture, or based on a conjecture.In conjectural statements, the French often use the Future or the Conditional, instead of the Perfect or the Pluperfect used in English. — 1863 noun1 •Something that is conjectural; a conjecture.Let us not assume such previous conjecturals, but rather consult and expostulate death, since death is the wages and the reward of sin. — 1821 formsconjecturals · more conjectural · most conjectural