The Collaborative International Dictionary of English v.0.48:

Imposthumate \Im*post"hu*mate\, v. t. [See Imposthume.]
   To apostemate; to form an imposthume or abscess. --Arbuthnot.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Imposthumate \Im*post"hu*mate\, v. t. [imp. & p. p.
   Imposthumated; p. pr. & vb. n. Imposthumating.]
   To affect with an imposthume or abscess.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Imposthumate \Im*post"hu*mate\, a.
   Imposthumated.
   [1913 Webster]