Seal1  —n. 1 piece of stamped wax, lead, paper, etc., attached to a document or to a receptacle, envelope, etc., to guarantee authenticity or security. 2 engraved piece of metal etc. For stamping a design on a seal. 3 substance or device used to close a gap etc. 4 anything regarded as a confirmation or guarantee (seal of approval). 5 decorative adhesive stamp. —v. 1 close securely or hermetically. 2 stamp, fasten, or fix with a seal. 3 certify as correct with a seal or stamp. 4 (often foll. By up) confine securely. 5 settle or decide (their fate is sealed). 6 (foll. By off) prevent entry to or exit from (an area).  set one's seal to (or on) authorize or confirm. [latin sigillum]