1. (Science: zoology) 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 sanil. Any gastropod having a general resemblance to the true snails, including fresh water and marine species. See pond snail, under Pond, and sea snail.
3. (Science: mechanics) 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. 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))
(Science: botany) Snail clover See Snail clover, above.
Origin: OE. Snaile, AS. Sngel, snegel, sngl; akin to G. Schnecke, OHG. Snecko, Dan. Snegl, Icel. Snigill.