An Etymological Dictionary of Astronomy and Astrophysics

1a) The formation or expression of an opinion or theory without sufficient evidence for proof. → mathematical conjecture.

1b) An opinion or theory so formed or expressed; → guess; → speculation.

2. To conclude or suppose from grounds or evidence insufficient to ensure reliability (Dictionary.com).
   
   

An opinion or theory formed without sufficient evidence for proof; guess; speculation.

Etymology (EN): M.E., from O.Fr. conjecture “surmise, guess,” or directly from L. coniectura “conclusion, interpretation, guess, inference,” literally “a casting together (of facts, etc.),” from coniectus, p.p. of conicere “to throw together,” from → com- “together” + iacere “to throw,” → eject.

Etymology (PE): Hâšan, from hâ-, variant ham-, → com-,

• šan, from ešândan “to throw out,” → eject.