discredit

transitive verb

1. to reject as untrue; disbelieve
2. to be a reason for disbelieving or distrusting; cast doubt on: their earlier lies discredit anything they may say
3. to damage the credit or reputation of; disgrace

noun

1. absence or loss of belief or trust; disbelief; doubt
2. damage to one's reputation; loss of respect or status; disgrace; dishonor
3. something that causes disgrace or loss of status