Source : Webster's Revised Unabridged Dictionary (1913)

Seal \Seal\, n. [OE. seel, OF. seel, F. sceau, fr. L. sigillum a
   little figure or image, a seal, dim. of signum a mark, sign,
   figure, or image. See {Sign}, n., and cf. {Sigil}.]
   1. 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.

   2. 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.

            Till thou canst rail the seal from off my bond Thou
            but offend;st thy lungs to speak so loud. --Shak.

   3. That which seals or fastens; esp., the wax or wafer placed
      on a letter or other closed paper, etc., to fasten it.

   4. That which confirms, ratifies, or makes stable; that which
      authenticates; that which secures; assurance. ``under the
      seal of silence.'' --Milton.

            Like a red seal is the setting sun On the good and
            the evil men have done.               --Lonfellow.

   5. 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.

   {Great seal}. See under {Great}.

   {Privy seal}. See under {Privy}, a.

   {Seal lock}, a lock in which the keyhole is covered by a seal
      in such a way that the lock can not be opened without
      rupturing the seal.

   {Seal manual}. See under {Manual}, a.

   {Seal ring}, a ring having a seal engraved on it, or
      ornamented with a device resembling a seal; a signet ring.
      --Shak.

Seal \Seal\ (s[=e]l), n. [OE. sele, AS. seolh; akin to OHG.
   selah, Dan. s[ae]l, Sw. sj["a]l, Icel. selr.] (Zo["o]l.)
   Any aquatic carnivorous mammal of the families {Phocid[ae]}
   and {Otariid[ae]}.

   Note: Seals inhabit seacoasts, and are found principally in
         the higher latitudes of both hemispheres. There are
         numerous species, bearing such popular names as {sea
         lion}, {sea leopard}, {sea bear}, or {ursine seal},
         {fur seal}, and {sea elephant}. The bearded seal
         ({Erignathus barbatus}), the hooded seal ({Cystophora
         crustata}), and the ringed seal ({Phoca f[oe]tida}),
         are northern species. See also {Eared seal}, {Harp
         seal}, and {Fur seal}, under {Eared}, {Harp}, {Monk},
         and {Fur}. Seals are much hunted for their skins and
         fur, and also for their oil, which in some species is
         very abundant.

   {Harbor seal} (Zo["o]l.), the common seal ({Phoca vitulina}).
      It inhabits both the North Atlantic and the North Pacific
      Ocean, and often ascends rivers; -- called also {marbled
      seal}, {native seal}, {river seal}, {bay seal}, {land
      seal}, {sea calf}, {sea cat}, {sea dog}, {dotard},
      {ranger}, {selchie}, {tangfish}.

Seal \Seal\, v. i.
   To affix one's seal, or a seal. [Obs.]

         I will seal unto this bond.              --Shak.

Seal \Seal\, v. t. [imp. & p. p. {Sealed}; p. pr. & vb. n.
   {Skaling}.] [OE. selen; cf. OF. seeler, seieler, F. sceller,
   LL. sigillare. See {Seal} a stamp.]
   1. To set or affix a seal to; hence, to authenticate; to
      confirm; to ratify; to establish; as, to seal a deed.

            And with my hand I seal my true heart's love.
                                                  --Shak.

   2. 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.

   3. To fasten with a seal; to attach together with a wafer,
      wax, or other substance causing adhesion; as, to seal a
      letter.

   4. Hence, to shut close; to keep close; to make fast; to keep
      secure or secret.

            Seal up your lips, and give no words but ``mum''.
                                                  --Shak.

   5. To fix, as a piece of iron in a wall, with cement,
      plaster, or the like. --Gwilt.

   6. To close by means of a seal; as, to seal a drainpipe with
      water. See 2d {Seal}, 5.

   7. Among the Mormons, to confirm or set apart as a second or
      additional wife. [Utah, U.S.]

            If a man once married desires a second helpmate . .
            . she is sealed to him under the solemn sanction of
            the church.                           --H.
                                                  Stansbury.

Source : WordNet®

seal
     n 1: fastener consisting of a resinous composition that is
          plastic when warm; used for sealing documents and
          parcels and letters [syn: {sealing wax}]
     2: a device incised to make an impression; used to secure a
        closing or to authenticate documents [syn: {stamp}]
     3: the pelt or fur (especially the underfur) of a seal; "a coat
        of seal" [syn: {sealskin}]
     4: a member of a Naval Special Warfare unit who is trained for
        unconventional warfare; "SEAL is an acronym for Sea Air
        and Land" [syn: {Navy SEAL}]
     5: a stamp affixed to a document (as to attest to its
        authenticity or to seal it); "the warrant bore the
        sheriff's seal"
     6: an indication of approved or superior status [syn: {cachet},
         {seal of approval}]
     7: a finishing coat applied to exclude moisture
     8: fastener that provides a tight and perfect closure
     9: any of numerous marine mammals that come on shore to breed;
        chiefly of cold regions

seal
     v 1: close with or as if with a seal; "She sealed the letter with
          hot wax" [ant: {unseal}]
     2: make tight; secure against leakage; "seal the windows" [syn:
         {seal off}]
     3: decide irrevocably; "sealing dooms"
     4: affix a seal to; "seal the letter"
     5: cover with varnish [syn: {varnish}]
     6: hunt seals

Source : Free On-Line Dictionary of Computing

SEAL
     
        Semantics-directed Environment Adaptation Language.
     
        {(ftp://ftp.cwi.nl/pub/gipe/0092b.ps.Z)}.