The Collaborative International Dictionary of English v.0.48:

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. (Zool.)
      (a) Any one of numerous species of terrestrial
          air-breathing gastropods belonging to the genus Helix
          and many allied genera of the family Helicidae. 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.
          [1913 Webster]

   2. Hence, a drone; a slow-moving person or thing.
      [1913 Webster]

   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.
      [1913 Webster]

   4. A tortoise; in ancient warfare, a movable roof or shed to
      protect besiegers; a testudo. [Obs.]
      [1913 Webster]

            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.).
      [1913 Webster]

   5. (Bot.) The pod of the sanil clover.
      [1913 Webster]

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

   Snail borer (Zool.), a boring univalve mollusk; a drill.

   Snail clover (Bot.), a cloverlike plant (Medicago
      scuttellata, also, Medicago 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 (Zool.), the shell of snail.

   Snail trefoil. (Bot.) See Snail clover, above.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pond \Pond\, n. [Probably originally, an inclosed body of water,
   and the same word as pound. See Pound an inclosure.]
   A body of water, naturally or artificially confined, and
   usually of less extent than a lake. "Through pond or pool."
   --Milton.
   [1913 Webster]

   Pond hen (Zool.), the American coot. See Coot
   (a) .

   Pond lily (Bot.), the water lily. See under Water, and
      Illust. under Nymph[ae]a.

   Pond snail (Zool.), any gastropod living in fresh-water
      ponds or lakes. The most common kinds are air-breathing
      snails (Pulmonifera) belonging to Limn[ae]a, Physa,
      Planorbis, and allied genera. The operculated species are
      pectinibranchs, belonging to Melantho, Valvata, and
      various other genera.

   Pond spice (Bot.), an American shrub (Tetranthera
      geniculata) of the Laurel family, with small oval leaves,
      and axillary clusters of little yellow flowers. The whole
      plant is spicy. It grows in ponds and swamps from Virginia
      to Florida.

   Pond tortoise, Pond turtle (Zool.), any freshwater
      tortoise of the family Emydid[ae]. Numerous species are
      found in North America.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Limnaea \Lim*n[ae]"a\ (l[i^]m*n[=e]"[.a]), prop. n. [NL., fr.
   Gr. limnai^os pertaining to a marsh, fr. li`mh a marsh.]
   (Zool.)
   A genus of fresh-water air-breathing mollusks, abundant in
   ponds and streams; -- called also pond snail. [Written also
   Lymn[ae]a.]
   [1913 Webster]