Source : Webster's Revised Unabridged Dictionary (1913)

Snail \Snail\ (sn[=a]l), n. [OE. snaile, AS. sn[ae]gel, snegel,
   sn[ae]gl; akin to G. schnecke, OHG. snecko, Dan. snegl, Icel.
   snigill.]
   1. (Zo["o]l.)
      (a) Any one of numerous species of terrestrial
          air-breathing gastropods belonging to the genus Helix
          and many allied genera of the family {Helicid[ae]}.
          They are abundant in nearly all parts of the world
          except the arctic regions, and feed almost entirely on
          vegetation; a land snail.
      (b) Any gastropod having a general resemblance to the true
          snails, including fresh-water and marine species. See
          {Pond snail}, under {Pond}, and {Sea snail}.

   2. Hence, a drone; a slow-moving person or thing.

   3. (Mech.) A spiral cam, or a flat piece of metal of spirally
      curved outline, used for giving motion to, or changing the
      position of, another part, as the hammer tail of a
      striking clock.

   4. A tortoise; in ancient warfare, a movable roof or shed to
      protect besiegers; a testudo. [Obs.]

            They had also all manner of gynes [engines] . . .
            that needful is [in] taking or sieging of castle or
            of city, as snails, that was naught else but hollow
            pavises and targets, under the which men, when they
            fought, were heled [protected], . . . as the snail
            is in his house; therefore they cleped them snails.
                                                  --Vegetius
                                                  (Trans.).

   5. (Bot.) The pod of the sanil clover.

   {Ear snail}, {Edible snail}, {Pond snail}, etc. See under
      {Ear}, {Edible}, etc.

   {Snail borer} (Zo["o]l.), a boring univalve mollusk; a drill.
      

   {Snail clover} (Bot.), a cloverlike plant ({Medicago
      scuttellata}, also, {M. Helix}); -- so named from its
      pods, which resemble the shells of snails; -- called also
      {snail trefoil}, {snail medic}, and {beehive}.

   {Snail flower} (Bot.), a leguminous plant ({Phaseolus
      Caracalla}) having the keel of the carolla spirally coiled
      like a snail shell.

   {Snail shell} (Zo["o]l.), the shell of snail.

   {Snail trefoil}. (Bot.) See {Snail clover}, above.