To mathematics, roughly what 'hypothesis' is to science. A conjecture is not a blind guess; it is a conclusion based on evidence and thought, but not yet confirmed with proof. After a conjecture has been verified by proof, it is a Theorem.
From Latin con- + -jec from Indo-European ye-, 'throw.' A 'conjecture' is a conclusion or interpretation 'thrown together' or put together mentally.
In related words, the -jec is usually seen as ject but also, sometimes, as jac.
Related mathematical terms
Other related words
abject, adjective, inject (throw in), interject (throw between), gist, jet, project, reject, subject, trajectory.