In the nature of a conjecture, or based on a conjecture.

Something that is conjectural; a conjecture.

In a conjectural manner.

plural of conjectural

The property of being conjectural.

(philosophy) The belief that intentionally supposing that a proposition is true is a good reason to believe that proposition in the absence of evidence of its falsehood.

present participle of conjecture

The forming of conjectures.

(formal) A statement or an idea which is unproven, but is thought to be true; a guess. / (formal) A supposition based upon incomplete evidence; a hypothesis.

(formal, intransitive) To guess; to venture an unproven idea. / (transitive) To infer on slight evidence; to guess at.