Definition of seal

• n. - Any aquatic carnivorous mammal of the families Phocidae and Otariidae.
• n. - An engraved or inscribed stamp, used for marking an impression in wax or other soft substance, to be attached to a document, or otherwise used by way of authentication or security.
• n. - Wax, wafer, or other tenacious substance, set to an instrument, and impressed or stamped with a seal; as, to give a deed under hand and seal.
• n. - That which seals or fastens; esp., the wax or wafer placed on a letter or other closed paper, etc., to fasten it.
• n. - That which confirms, ratifies, or makes stable; that which authenticates; that which secures; assurance.
• n. - An arrangement for preventing the entrance or return of gas or air into a pipe, by which the open end of the pipe dips beneath the surface of water or other liquid, or a deep bend or sag in the pipe is filled with the liquid; a draintrap.
• v. t. - To set or affix a seal to; hence, to authenticate; to confirm; to ratify; to establish; as, to seal a deed.
• v. t. - To mark with a stamp, as an evidence of standard exactness, legal size, or merchantable quality; as, to seal weights and measures; to seal silverware.
• v. t. - To fasten with a seal; to attach together with a wafer, wax, or other substance causing adhesion; as, to seal a letter.
• v. t. - Hence, to shut close; to keep close; to make fast; to keep secure or secret.
• v. t. - To fix, as a piece of iron in a wall, with cement, plaster, or the like.
• v. t. - To close by means of a seal; as, to seal a drainpipe with water. See 2d Seal, 5.
• v. t. - Among the Mormons, to confirm or set apart as a second or additional wife.
• v. i. - To affix one's seal, or a seal.