impeach in WordNet English dictionary

1. bring an accusation against; level a charge against
   "The neighbors accused the man of spousal abuse"
   accuse  impeach  incriminate  criminate 
   
2. charge (a public official) with an offense or misdemeanor committed while in office
   "The President was impeached"
   impeach 
   
3. challenge the honesty or veracity of
   "the lawyers tried to impeach the credibility of the witnesses"
   impeach