seal

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various aquatic carnivorous mammals of the families Phocidae and Otariidae, found chiefly in cold regions and having a sleek torpedo-shaped body and limbs that are modified into paddlelike flippers.
• noun The pelt or fur of one of these animals, especially a fur seal.
• noun Leather made from the hide of one of these animals.
• intransitive verb To hunt seals.
• noun A device or material that is used to close off or fasten an opening or connection, especially to prevent the escape of a liquid or gas.
• noun An airtight closure.
• noun Something, such as a piece of tape, that is placed on a product or package to show that the contents have not been tampered with.
• noun The water in the trap of a drain that prevents sewer gas from escaping into a room.
• noun A design used to identify a person or thing or to show that something is authentic, accurate, or of good quality.
• noun A small decorative paper sticker.
• noun A die or signet having a raised or incised emblem used to stamp an impression on a receptive substance such as wax or lead.
• noun The impression so made.
• noun The design or emblem itself, belonging exclusively to the user.
• noun A small disk or wafer of wax, lead, or paper bearing such an imprint and affixed to a document to prove authenticity or to secure it.
• noun An indication or symbol regarded as guaranteeing or authenticating something.
• transitive verb To close or fasten with a seal.
• transitive verb To prevent (a liquid or gas) from escaping.
• transitive verb To cover, secure, or fill up (an opening).
• transitive verb To apply a waterproof coating to.
• transitive verb To secure or prevent passage into and out of (an area). Often used with off:
• transitive verb To affix a seal to (something) in order to prove authenticity, accuracy, or quality.
• transitive verb To establish or determine irrevocably.
• transitive verb Mormon Church To make (a marriage, for example) eternally binding; solemnize forever.
• idiom ((one's) lips are sealed) Used to indicate that one will not disclose a piece of information.
• idiom (under seal) Having an impression or emblem attesting to a document's authenticity and reliability.

from The Century Dictionary.

• To hunt or catch seals.
• noun A marine car nivorous mammal of the order Feræ, suborder Pinnipedia, and family Phocidæ or Otariidæ; any pinniped not a walrus—for example, a hair-seal, a fur-seal, an eared seal, of which there are numerous genera and species.
• noun In heraldry, a bearing representing a creature something like a walrus, with a long fish-like body and the head of a carnivorous animal.
• noun Sealskin; leather made from the skin of the seal.
• noun The amount of lap over the edge of an opening by which a lid or valve projects to make a tight joint and prevent leakage past it.
• noun See day.
• See seel.
• To set or affix a seal to, as a mark of authenticity, confirmation, or execution: as, to seal a deed.
• To stamp, as with a seal.
• Specifically
• To certify with a stamp or mark; stamp as an evidence of standard exactness, legal size, or merchantable quality: as, to seal weights and measures; to seal leather.
• To attest; affirm; bear witness to the truth or genuineness of, by some outward act: as, to seal one's loyalty with one's life; hence, to confirm; ratify; establish; fix.
• To grant authoritatively or under seal.
• To fasten or secure with a seal, or with some fastening bearing a seal; close or secure with sealing-wax, a wafer, or the like: as, to seal a letter.
• To shut up or close: as, to seal a book; to seal one's lips or eyes; hence, to establish; determine irrevocably.
• To mark; designate; appoint.
• To set apart or give in marriage, according to the system of plural marriages prevalent among the Mormons of Utah.
• To inclose; confine; imprison.
• In hydraul., sanitary engin., etc., to secure against a flow or escape of air or gas, as by the use of a dip-pipe in any form.
• In architecture, to fix, as a piece of wood or iron in a wall, with cement, plaster, or other binding material for staples, hinges, etc.
• To close the chinks of, as a log house, with plaster, clay, or the like.