to attest as certain; give reliable information of; confirm

He certified the truth of his claim.

to testify to or vouch for in writing

The medical examiner will certify his findings to the court.

to guarantee; endorse reliably

to certify a document with an official seal.

to guarantee (a check) by writing on its face that the account against which it is drawn has sufficient funds to pay it.

to award a certificate to (a person) attesting to the completion of a course of study or the passing of a qualifying examination.

to declare legally insane and committable to a mental institution.

Archaic . to assure or inform with certainty.

to give assurance; testify; vouch for the validity of something (usually fol. by to ).

verb

contradict , counteract , deny , disavow , discredit , invalidate , reject , repudiate

verb

accredit , approve , ascertain , assure , attest , authenticate , authorize , aver , avow , commission , confirm , corroborate , endorse , guarantee , license , notify , okay , profess , reassure , rubber-stamp , sanction , show , state , swear , testify , validate , verify , vouch , witness , guaranty , warrant , affirm , depose , determine , notarize , testify to , vouch for