OK
accept
accredit
affirm
amen
approve
attest
authorize
autograph
avouch
back
back up
bear out
bolster
buttress
canonize
certify
circumstantiate
confirm
corroborate
cosign
countersign
demonstrate
document
endorse
fortify
give permission
give the go-ahead
give the imprimatur
give thumbs up
initial
justify
notarize
pass
pass on
pass upon
permit
probate
prove
ratify
reinforce
rubber stamp
sanction
say amen to
seal
second
sign
sign and seal
strengthen
subscribe to
evidence
manifest
authenticated
authenticates
authenticating