certify

[1]	confirm , attest , manifest , attest (to) , verify , demonstrate , evidence , testify (to) , affirm , aver , asseverate , corroborate , substantiate , endorse , guarantee , warrant , swear (to) , bear witness (to) , vouchsafe , vouch (for)
[2]	declare , classify , establish , confirm
[3]	license , licence
[4]	indorse