The Collaborative International Dictionary of English v.0.48:

Misconjecture \Mis`con*jec"ture\ (?; 135), n.
   A wrong conjecture or guess. --Sir T. Browne.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Misconjecture \Mis`con*jec"ture\, v. t. & i.
   To conjecture wrongly.
   [1913 Webster]