1. guesswork: the formation of judgments or opinions on the basis of incomplete or inconclusive information The origin of this ritual is a matter of conjecture.
2. something guessed: a conclusion, judgment, or statement based on incomplete or inconclusive information
3. mathematics science unproved theorem: a theorem in science or mathematics that has still to be proved
[14th century. Directly or via French< Latin conjectura< conjicere "throw together" < jacere "throw"]