The Collaborative International Dictionary of English v.0.48:

Nefand \Ne"fand\, Nefandous \Ne*fan"dous\, a. [L. nefandus not
   to be spoken; ne not + fari to speak.]
   Unfit to speak of; unmentionable; impious; execrable. [Obs.]
   "Nefand adominations." --Sheldon. "Nefandous high treason."
   --Cotton Mather.
   [1913 Webster]