the formation or expression of an opinion or theory without sufficient evidence for proof.

an opinion or theory so formed or expressed; guess; speculation.

Obsolete . the interpretation of signs or omens.

to conclude or suppose from grounds or evidence insufficient to ensure reliability.

to form conjectures.

noun

fact , proof , reality , truth

verb

prove

noun

conclusion , fancy , guess , guesstimate , guesswork , hunch , hypothesis , inference , notion , opinion , perhaps , presumption , shot in the dark * , sneaking suspicion , stab in the dark , supposition , surmise , theorizing , theory , speculation , belief , postulation , speculate , supposition.--v. surmise , theorem , thought

verb

assume , believe , conceive , conclude , deem , estimate , expect , fancy , feel * , figure , gather , glean , guess , guesstimate , hazard a guess , hypothesize , imagine , infer , judge , presume , pretend , suppose , surmise , suspect , take a shot , take a stab , take for granted , theorize , think , speculate , assumption , belief , conclusion , divine , estimation , idea , inference , judgment , opine , opinion , plot , postulate , presuppose , speculation , supposition , suspicion , theory , view