\Ob*ver"sion\, n. [L. obversio a turning towards.]
1. The act of turning toward or downward.
2. (Logic) The act of immediate inference, by which we deny
   the opposite of anything which has been affirmed; as, all
   men are mortal; then, by obversion, no men are immortal.
   This is also described as ``immediate inference by
   privative conception.'' --Bain.