impeach

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To make an accusation against.
2. v. To charge (a public official) with improper conduct in office before a proper tribunal.
3. v. To challenge the validity of; try to discredit: impeach a witness's credibility.

Century Dictionary and Cyclopedia

1. n. Same as impeachment.
2. To hinder; impede.
3. To call in question; accuse of wrong or error; bring discredit on; disparage; accuse: as, to impeach one's motives; to impeach the credit of a witness.
4. Specifically, to prefer charges of official misconduct against, before a competent tribunal; bring to account by trial for malfeasance in office. See impeachment, 3.
5. To call to account; charge as answerable.

Wiktionary

1. v. To hinder.
2. v. To bring a legal proceeding against a public official, asserting that because he or she committed some offense, he or she should be removed from office.
3. v. To discredit an individual or group with presumed expertise.

GNU Webster's 1913

1. n. Hindrance; impeachment.
2. v. To hinder; to impede; to prevent.
3. v. To charge with a crime or misdemeanor; to accuse; especially to charge (a public officer), before a competent tribunal, with misbehavior in office; to cite before a tribunal for judgment of official misconduct; to arraign. See Impeachment.
4. v. Hence, to charge with impropriety; to dishonor; to bring discredit on; to call in question.
5. v. To challenge or discredit the credibility of, as of a witness, or the validity of, as of commercial paper.

WordNet 3.0

1. v. challenge the honesty or veracity of
2. v. bring an accusation against; level a charge against
3. v. charge (a public official) with an offense or misdemeanor committed while in office