shell

noun

1. 1.

   The hard outer covering of an animal such as a snail, turtle, or crustacean.

2. 2.

   The outer casing of an egg, nut, or seed.

3. 3.

   A metal case filled with explosive, fired from a gun.

4. 4.

   [computing]A program providing user interface to the operating system.

5. 5.

   [as verb]To remove from a shell; to bombard.