Conjecture
Part of speech: noun
Definition: A statement or an idea which is unproven, but is thought to be true; a guess. A supposition based upon incomplete evidence; a hypothesis. A statement likely to be true based on available evidence, but which has not been formally proven. The interpretation of signs and omens.
Part of speech: verb
Definition: To guess; to venture an unproven idea.
Example sentence: It seems likely that Jesus, being a scholarly young man, learned some Hebrew, but that's conjecture. It's more likely that Jesus spoke some Greek, as this language dominated the region after the conquests of Alexander the Great in the fourth century.
Surmise
Part of speech: noun
Definition: Thought, imagination, or conjecture, which may be based upon feeble or scanty evidence; suspicion; guess; as, surmises of jealousy or of envy.Reflection; thought; posit.
Part of speech: verb
Definition: To conjecture, to opine or to posit with contestable premises.