noun

1. a hard outer covering, as of a turtle, mollusk, insect, egg, fruit, seed, etc.
2. something like or suggestive of a shell in being hollow, empty, or simply a covering or framework, as the hull of a boat, a hollow pastry or unfilled pie crust, the framework of a building, a structure with an arched or hemispherical roof or back, a tapered beer glass, etc.
3. a shy, reserved, or uncommunicative attitude or manner to come out of one's shell
4. ☆ a woman's simple sleeveless blouse or sweater
5. ☆ a long, narrow, thin-hulled racing boat rowed usually by a team of oarsmen
6. an explosive artillery projectile containing high explosives and sometimes shrapnel, chemicals, etc.
7. ☆ a cartridge for small arms or small artillery, consisting of a metal, paper, or plastic case holding the primer, powder charge, and shot or bullet
8. a pyrotechnic cartridge which explodes high in the air
9. 1. a mollusk
   2. shellfish
10. Chem., Physics
    1. any of the spherical or elliptical orbits of electrons around the nucleus of an atom, each with the same principal quantum number and about the same energy
    2. the space taken up by such an orbit
    3. a grouping of like nucleons of approximately the same energy in the nucleus

Etymology: ME schelle < OE sciel, akin to MDu schelle < IE base *(s)kel-: see shelf

transitive verb

1. to remove the shell or covering from; take out of the shell to shell peas, oysters, etc.
2. to separate kernels or grains of (corn, wheat, etc.) from the cob or ear
3. to fire shells at from a large gun or guns; bombard

intransitive verb

1. to separate from the shell or covering peanuts shell easily
2. to fall, slough, or peel off, as a shell
3. ☆ to gather or collect shells