Source : Webster's Revised Unabridged Dictionary (1913)

Impoverish \Im*pov"er*ish\, v. t. [imp. & p. p. {Impoverished};
   p. pr. & vb. n. {Impoverishing}.] [OF. empovrir; pref. em-
   (L. in) + povre poor, F. pauvre; cf. OF. apovrir, F.
   appauvrir, where the prefix is a-, L. ad. Cf. {Empoverish},
   and see {Poor}, and {-ish}.]
   1. To make poor; to reduce to poverty or indigence; as,
      misfortune and disease impoverish families.

   2. To exhaust the strength, richness, or fertility of; to
      make sterile; as, to impoverish land.

Source : WordNet®

impoverish
     v 1: make poor [ant: {enrich}]
     2: take away [syn: {deprive}] [ant: {enrich}]