1. a. The usually hard outer covering that encases certain organisms, such as mollusks, insects, and turtles; the carapace. b. A similar outer covering on an egg, a fruit, or a nut. c. The material that constitutes such a covering.

2. Something resembling or having the form of a shell, especially: a. An external, usually hard, protective or enclosing case or cover. b. A framework or an exterior, as of a building. c. A thin layer of pastry. d. The external part of the ear.

3. Nautical. a. The hull of a ship. b. A long, narrow racing boat propelled by rowers.

4. A small glass for beer.

5. a. A projectile or piece of ammunition, especially the hollow tube containing explosives used to propel such a projectile. b. A metal or cardboard case containing the charge, primer, and shot fired from a shotgun.

6. An attitude or a manner adopted to mask one's true feelings.

7. Physics. a. Any of the set of hypothetical spherical surfaces centered on the nucleus of an atom that contain the orbitals of electrons having the same principal quantum number. b. An analogous pattern of protons and neutrons within a nucleus.

8. a. A usually sleeveless and collarless, typically knit blouse. b. The outermost layer of a lined garment such as a coat or jacket: a parka with a waterproof shell.

9. Computer Science. A program that works with the operating system as a command processor, used to enter commands and initiate their execution.

1. a. To remove the shell of; shuck: shell oysters. b. To remove from a shell: shell peas.

2. To separate the kernels of (corn) from the cob.

3. To fire shells at; bombard.

4. a. To defeat decisively. b. Baseball. To hit the pitches of (a pitcher) hard and with regularity: shelled the pitcher for eight runs in the first inning.

1. To shed or become free of a shell.

2. To look for or collect shells, as on a seashore: spent the day shelling on Cape Cod.