1. (n.) The act of writing on the back of a note, bill, or other written instrument.

2. (n.) That which is written on the back of a note, bill, or other paper, as a name, an order for, or a receipt of, payment, or the return of an officer, etc.; a writing, usually upon the back, but sometimes on the face, of a negotiable instrument, by which the property therein is assigned and transferred.

3. (n.) Sanction, support, or approval; as, the endorsement of a rumor, an opinion, a course, conduct.

John Hancock OK X acceptance accord acquiescence adherence admiration affirmance affirmation affirmative affirmative voice agreement approbation approval assent authentication authorization autograph aye backing blessing certification christcross cipher compliance confirmation connivance consent countenance countermark countersign countersignature counterstamp cross device eagerness esteem favor favorable vote fiat go-ahead green light hand imprimatur indorsement initials mark mark of signature monogram nod notarization okay permission promptitude promptness ratification readiness respect rubber stamp sanction seal seal of approval sigil sign manual signature signet stamp stamp of approval submission subscription support the nod ungrudgingness unloathness unreluctance validation visa vise voice vote warrant willingness yea yea vote