Emily Dickinson Lexicon

AT-TEST', v.t. [Fr. attester; L. attestor; of ad and testor, to affirm or bear witness, from testis. See Testify.]

1. To bear witness to; to certify; to affirm to be true or genuine; to make a solemn declaration in words or writing, to support a fact; appropriately used for the affirmation of persons in their official capacity; as, to attest the truth of a writing; to attest a copy of record. Persons also attest writings by subscribing their names.
2. To bear witness, or support the truth of a fact, by other evidence than words; as, the ruins of Palmyra attest its ancient magnificence.
3. To call to witness; to invoke as conscious. The sacred streams which heaven's imperial state Attests in oaths, and fears to violate. – Dryden.