transitive verb certified -·fied′, certifying -·fy′·ing

1. to declare (a thing) true, accurate, certain, etc. by formal statement, often in writing; verify; attest
2. to declare officially insane and committable to a mental institution
3. ☆ to guarantee the quality or worth of (a check, document, etc.); vouch for
4. to issue a certificate or license to
5. Archaic to assure; make certain

Etymology: ME certifien < OFr certifier < LL certificare < L certus, certain + -fy

intransitive verb