vouch

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To give personal assurances; give a guarantee: vouch for an old friend's trustworthiness.
2. v. To constitute supporting evidence; give substantiation: a candidate whose strong record vouches for her ability.
3. v. To substantiate by supplying evidence; prove: charges that he could not vouch.
4. v. Law To summon as a witness to give warranty of title.
5. v. To refer to (an authority, for example) in support or corroboration; cite.
6. v. To assert; declare.
7. n. Obsolete A declaration of opinion; an assertion.

Century Dictionary and Cyclopedia

1. To call to witness.
2. To declare; assert; affirm; attest; avouch.
3. To warrant; be surety for; answer for; make good; confirm.
4. To support; back; second; follow up.
5. In law: To produce vouchers for, in support of a charge in account.
6. In old English law, to call or summon into court to warrant and defend, or to make good a warranty of title.
7. Synonyms To asseverate, aver, protest.
8. To bear witness; give testimony or attestation: more specifically, in old English law, to call in some one to make good his alleged warranty of title; be surety or guaranty.
9. n. Approving or supporting warrant; confirmation; attestation.

Wiktionary

1. v. To take responsibility for; to express confidence in; to witness; to obtest.
2. v. To warrant; to maintain by affirmations; to attest; to affirm; to avouch.
3. v. To back; to support; to confirm.
4. v. To call into court to warrant and defend, or to make good a warranty of title.
5. v. To bear witness; to give testimony or full attestation.
6. v. To assert; to aver; to declare.
7. n. Warrant; attestation.

GNU Webster's 1913

1. v. obsolete To call; to summon.
2. v. To call upon to witness; to obtest.
3. v. To warrant; to maintain by affirmations; to attest; to affirm; to avouch.
4. v. To back; to support; to confirm; to establish.
5. v. (Law) To call into court to warrant and defend, or to make good a warranty of title.
6. v. To bear witness; to give testimony or full attestation.
7. v. To assert; to aver; to declare.
8. n. obsolete Warrant; attestation.

WordNet 3.0

1. v. give personal assurance; guarantee.
2. v. give supporting evidence
3. v. give surety or assume responsibility
4. v. summon (a vouchee) into court to warrant or defend a title