1. To declare the provable truth or validity of; to affirm: Mr. Smith avouched that his son, Tim, could not have committed the crime.
2. To corroborate or to confirm; to verify: Was the police officer able to avouch his accusations about the boy?
3. To accept responsibility for and to acknowledge responsibility for doing something: When Richard and Greg both had exactly the same answers on their tests, Greg avouched that he was the one who copied from Richard.
4. To avow or to confess: Tom avouched or admitted that he had eaten some of the cake and not his brother!
5. Etymology: from Middle French avochier, "call upon as authority"; from Old French and Latin advocare, "to call to" as a witness.