attest

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To affirm to be correct, true, or genuine.
• intransitive verb To certify by signature or oath.
• intransitive verb To certify in an official capacity.
• intransitive verb To supply or be evidence of: synonym: indicate.
• intransitive verb Linguistics To confirm the existence, usage, or currency of (a word, for example), as by being recorded in writing.
• intransitive verb To put under oath.
• intransitive verb To bear witness; give testimony.
• noun Archaic Attestation.

from The Century Dictionary.

• noun Witness; testimony; attestation.
• To bear witness to; certify; affirm to be true or genuine; declare the truth of in words or writing; especially, affirm in an official capacity: as, to attest the truth of a writing; to attest a copy of a document.
• To make evident; vouch for; give proof or evidence of; manifest.
• To call to witness; invoke as knowing or conscious.
• To put upon oath; swear in.
• To bear witness; make an attestation: with to: as, to attest to a statement or a document.

from the GNU version of the Collaborative International Dictionary of English.

• noun rare Witness; testimony; attestation.
• transitive verb To bear witness to; to certify; to affirm to be true or genuine.
• transitive verb To give proof of; to manifest.
• transitive verb Archaic To call to witness; to invoke.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb To affirm to be correct, true, or genuine.
• verb To certify by signature or oath
• verb To certify in an official capacity.
• verb To supply or be evidence of
• verb To put under oath.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb give testimony in a court of law
• verb provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
• verb authenticate, affirm to be true, genuine, or correct, as in an official capacity
• verb establish or verify the usage of