conjecture

A statement or an idea which is unproven, but is thought to be true; a guess.

“I explained it, but it is pure conjecture whether he understood, or not.”

A supposition based upon incomplete evidence; a hypothesis.

“The physicist used his conjecture about subatomic particles to design an experiment.”

(philology) A statement likely to be true based on available evidence, but which has not been formally proven.

Interpretation of signs and omens.

To guess; to venture an unproven idea.

“I do not know if it is true; I am simply conjecturing here.”

To infer on slight evidence; to guess at.