Shell  —n. 1 a hard outer case of many molluscs, the tortoise, etc. B hard but fragile case of an egg. C hard outer case of a nut-kernel, seed, etc. 2 a explosive projectile for use in a big gun etc. B hollow container for fireworks, cartridges, etc. 3 shell-like thing, esp.: a a light racing-boat. B the metal framework of a vehicle etc. C the walls of an unfinished or gutted building, ship, etc. —v. 1 remove the shell or pod from. 2  bombard with shells.  come out of one's shell become less shy. Shell out (also absol.) Colloq. Pay (money).  shell-less adj. Shell-like adj. [old english]