con·jec·ture / kənˈjekchər/ • n. an opinion or conclusion formed on the basis of incomplete information: conjectures about the newcomer the purpose of the wall is open to conjecture. ∎  an unproven mathematical or scientific theorem. ∎  (in textual criticism) the suggestion or reconstruction of a reading of a text not present in the original source.• v. [tr.] form an opinion or supposition about (something) on the basis of incomplete information: many conjectured that she had a second husband in mind. ∎  (in textual criticism) propose (a reading).DERIVATIVES: con·jec·tur·a·ble adj.

conjecture †interpretation of signs, etc. XIV; (formation of) an opinion on grounds insufficient for proof XVI. — (O)F. conjecture or L. conjectūra conclusion, inference, f. conject-, pp. stem of conicere throw together, put together in speech or thought, conclude; see CON-, ABJECT, -URE.
So conjecture vb. XIV. — (O)F. conjecturer — late L. conjecturāre. conjectural XVI. — F. — L.