Definition of Impoverish

Babylon English Dictionary
make poor, pauperize; take away the richness of, exhaust the strength of
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Impoverish Definition from Language, Idioms & Slang Dictionaries & Glossaries
Webster's Revised Unabridged Dictionary (1913)
(v. t.)
To make poor; to reduce to poverty or indigence; as, misfortune and disease impoverish families.
  
(v. t.)
To exhaust the strength, richness, or fertility of; to make sterile; as, to impoverish land.
  
Webster's Revised Unabridged Dictionary (1913), edited by Noah Porter. About
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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.

for Vocabulary Exams of KPDS, YDS,UDS (in Turkey); and SAT in America
To make indigent or poor.
WordNet 2.0

Verb
1. make poor
(antonym) enrich
(hypernym) deprive
(hyponym) reduce
(derivation) pauperization, pauperisation, impoverishment
2. take away
(synonym) deprive
(hypernym) worsen, decline
(hyponym) disestablish
(derivation) pauperization, pauperisation, impoverishment