Синоним endorse

sanction approve ratify recommend countersign authorise authorize validate certify support advocate affirm back commend confirm defend favor favour okay praise uphold accredit attest authenticate bless boost champion countenance guarantee push second sustain underwrite warrant witness back up give a boost to give green light give one's word give the go-ahead give the nod go along with go to bat for go with lend one's name to rubber-stamp stand behind stand up for stump for subscribe to vouch for

sign autograph cosign notarize subscribe superscribe undersign add one's name to put John Hancock on put signature on say amen to sign off on sign on dotted line