attest Copy link Outline 1. testor, 12. testĭfĭcor, 13. signo, 1 (i.e. to attest by one's signature or seal) • attest: 1. testor, 1: the plain a.s battles by its tombs, campus sepulcris proelia t., Hor. 2. testĭfĭcor, 1: v. to testify, BEAR WITNESS. 3. signo, 1 (i.e. to attest by one's signature or seal): v. to sign.