discredit

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To damage in reputation; disgrace.
2. v. To cause to be doubted or distrusted.
3. v. To refuse to believe.
4. n. Loss of or damage to one's reputation.
5. n. Lack or loss of trust or belief; doubt.
6. n. Something damaging to one's reputation or stature.

Century Dictionary and Cyclopedia

1. To disbelieve; give no credit to; not to credit or believe: as, the report is discredited.
2. To injure the credit or reputation of; make less esteemed or honored; fail to do credit to.
3. To deprive of credibility; destroy confidence in.
4. n. Want of credit or good repute; some degree of disgrace or reproach; disesteem: applied to persons or things: as, frauds that bring manufactures into discredit; a transaction much to his discredit.
5. n. Want of belif, trust, or confidence; disbelief: as, his story is received with discredit. Synonyms Disrepute, dishonor, ill repute.

Wiktionary

1. v. transitive To harm the good reputation of a person; to cause an idea or piece of evidence to seem false or unreliable.

GNU Webster's 1913

1. n. The act of discrediting or disbelieving, or the state of being discredited or disbelieved.
2. n. Hence, some degree of dishonor or disesteem; ill repute; reproach; -- applied to persons or things.
3. v. To refuse credence to; not to accept as true; to disbelieve.
4. v. To deprive of credibility; to destroy confidence or trust in; to cause disbelief in the accuracy or authority of.
5. v. To deprive of credit or good repute; to bring reproach upon; to make less reputable; to disgrace.

WordNet 3.0

1. v. damage the reputation of
2. v. cause to be distrusted or disbelieved
3. n. the state of being held in low esteem
4. v. reject as false; refuse to accept