The Collaborative International Dictionary of English v.0.48:

Impregnant \Im*preg"nant\, n. [See Impregnate.]
   That which impregnates. [R.] --Glanvill.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Impregnant \Im*preg"nant\, a. [Pref. im- not + pregnant.]
   Not pregnant; unfertilized or infertile. [R.]
   [1913 Webster]