Shell

1. a hard outer covering of an animal, as the hard case of a mollusk, or either half of the case of a bivalve mollusk. 2. any of various objects resembling such a covering, as in shape or in being more or less concave or hollow. 3. the material constituting any of various coverings of this kind. 4. the hard exterior of an egg. 5. the usually hard, outer covering of a seed, fruit, or the like, as the hard outside portion of a nut, the pod of peas, etc. 6. a hard, protecting or enclosing case or cover. 7. an attitude or manner of reserve that usually conceals one's emotions, thoughts, etc.: One could not penetrate his shell. 8. a hollow projectile for a cannon, mortar, etc., filled with an explosive charge designed to explode during flight, upon impact, or after penetration. 9. a metallic cartridge used in small arms and small artillery pieces. 10. a metal or paper cartridge, as for use in a shotgun. 11. a cartridgelike pyrotechnic device that explodes in the air. 12. shells, Italian Cookery. small pieces of pasta having the shape of a shell. 13. the lower pastry crust of a pie, tart, or the like, baked before the filling is added. 14. Computers. a program providing a menu-driven or graphical user interface designed to simplify use of the operating system, as in loading application programs. 15. Physics. any of up to seven energy levels on which an electron may exist within an atom, the energies of the electrons on the same level being equal and on different levels being unequal. a group of nucleons of approximately the same energy. 16. a light, long, narrow racing boat, for rowing by one or more persons. 17. the outer part of a finished garment that has a lining, especially a detachable lining. 18. a woman's sleeveless blouse or sweater, especially one meant for wear under a suit jacket. 19. Nautical. the plating, planking, or the like, covering the ribs and forming the exterior hull of a vessel. 20. tortoise shell (def 1). 21. a mollusk. 22. Engineering. the curved solid forming a dome or vault. 23. an arena or stadium covered by a domed or arched roof. 24. a saucer-shaped arena or stadium. 25. the framework, external structure, or walls and roof of a building: After the fire, only the shell of the school was left. 26. a small glass for beer. 27. the metal, pressure-resistant outer casing of a fire-tube boiler. 28. Metallurgy. a scab on the surface of an ingot. a length of unfinished tubing. a pierced forging. a hollow object made by deep drawing.