A hard external covering of an animal. • The calcareous or chitinous external covering of mollusks, crustaceans, and some other invertebrates. • Any mollusk having such a covering. • The exoskeleton or wing covers of certain insects. • The conjoined scutes that constitute the "shell" (carapace) of a tortoise or turtle. • The overlapping hard plates comprising the armor covering the armadillo's body. • The hard calcareous covering of a bird egg. • One of the outer layers of skin of an onion. • The hard external covering of various plant seed forms. • The covering, or outside part, of a nut. • A pod containing the seeds of certain plants, such as the legume Phaseolus vulgaris. • Husks of cacao seeds, a decoction of which is sometimes used as a substitute or adulterant for cocoa and its products such as chocolate. • The accreted mineral formed around a hollow geode. • The casing of a self-contained single-unit artillery projectile. • A hollow, usually spherical or cylindrical projectile fired from a siege mortar or a smoothbore cannon. It contains an explosive substance designed to be ignited by a fuse or by percussion at the target site so that it will burst and scatter at high velocity its contents and fragments. Formerly called a bomb. • The cartridge of a breechloading firearm; a load; a bullet; a round. • Any slight hollow structure; a framework, or exterior structure, regarded as not complete or filled in, as the shell of a house. • A garment, usually worn by women, such as a shirt, blouse, or top, with short sleeves or no sleeves, that often fastens in the rear. • A coarse or flimsy coffin; a thin interior coffin enclosed within a more substantial one. • An unmarked vehicle for carrying corpses from a crime scene. • A string instrument, as a lyre, whose acoustical chamber is formed like a shell. • The body of a drum; the often wooden, often cylindrical acoustic chamber, with or without rims added for tuning and for attaching the drum head. • An engraved copper roller used in print works. • The thin coating of copper on an electrotype. • The watertight outer covering of the hull of a vessel, often made with planking or metal plating. • The outer frame or case of a block within which the sheaves revolve. • A light boat whose frame is covered with thin wood, impermeable fabric, or water-proofed paper; a racing shell or dragon boat. • A set of atomic orbitals that have the same principal quantum number. • The outward form independent of what is inside. • The empty outward form of someone or something. • An emaciated person. • A person otherwise diminished. • A psychological barrier to social interaction. • An operating system software user interface, whose primary purpose is to launch other programs and control their interactions; the user's command interpreter. Shell is a way to separate the internal complexity of the implementation of the command from the user. The internals can change while the user experience/interface remains the same. • A legal entity that has no operations. • A concave rough cast-iron tool in which a convex lens is ground to shape. • A gouge bit or shell bit. • The onset and coda of a syllable. • A person's ear. • One or more school grades within secondary education, at certain public schools. • In formal debating, a set of proposed rules to be followed, with set penalties for violating them.