1. (v. t.) To cover the back of; to load or burden.

2. (v. t.) To write upon the back or outside of a paper or letter, as a direction, heading, memorandum, or address.

3. (v. t.) To write one's name, alone or with other words, upon the back of (a paper), for the purpose of transferring it, or to secure the payment of a note, draft, or the like; to guarantee the payment, fulfillment, performance, or validity of, or to certify something upon the back of (a check, draft, writ, warrant of arrest, etc.).

4. (v. t.) To give one's name or support to; to sanction; to aid by approval; to approve; as, to indorse an opinion.

OK abet accede to accept accord to accredit admire advocate affirm agree to aid and abet amen approve approve of assent assure attest authenticate authorize autograph back back up be sponsor for be willing bless bond certify comfort condescend confirm connive at consent consent to silently cosign countenance countersecure countersign deign elect embolden encourage endorse ensure esteem favor give consent give permission give the go-ahead give the imprimatur give thumbs up go along with go for grant guarantee guaranty have no objection hearten hold with initial insure keep in countenance nod nod assent nominate not refuse notarize okay pass pass on pass upon permit ratify respect rubber stamp sanction say amen to say aye say yes seal second secure shine upon sign sign and seal sign for smile upon sponsor stand behind stand up for subscribe subscribe to support swear and affirm swear to take kindly to think well of undersign underwrite uphold validate view with favor visa vise vote vote affirmatively vote aye warrant wink at yield assent