1. to declare or assert positively; to affirm or guarantee
Usage: formal; somewhat archaic
2. to acknowledge or admit openly
Usage: formal; literary

Examples

• The witness was willing to avouch the defendant’s whereabouts.
• I can avouch for his honesty and integrity.
• She avouched her commitment to the cause.
• The document avouches the authenticity of the signature.
• He avouched his mistake before the committee.
• The expert avouched the painting’s provenance.