a hard outside covering, as of a fruit or an animal.-the covering, or outside part, of a nut; as, a hazelnut shell.-a pod.-the hard covering of an egg.-the hard calcareous or chitinous external covering of mollusks, crustaceans, and some other invertebrates. in some mollusks, as the cuttlefishes, it is internal, or concealed by the mantle. also, the hard covering of some vertebrates, as the armadillo, the tortoise, and the like.-hence, by extension, any mollusks having such a covering.-a hollow projectile, of various shapes, adapted for a mortar or a cannon, and containing an explosive substance, ignited with a fuse or by percussion, by means of which the projectile is burst and its fragments scattered. see bomb.-the case which holds the powder, or charge of powder and shot, used with breechloading small arms.-any slight hollow structure; a framework, or exterior structure, regarded as not complete or filled in; as, the shell of a house.-a coarse kind of coffin; also, a thin interior coffin inclosed in a more substantial one.-an instrument of music, as a lyre, -- the first lyre having been made, it is said, by drawing strings over a tortoise shell.-an engraved copper roller used in print works.-the husks of cacao seeds, a decoction of which is often used as a substitute for chocolate, cocoa, etc.-the outer frame or case of a block within which the sheaves revolve.-a light boat the frame of which is covered with thin wood or with paper; as, a racing shell.-to strip or break off the shell of; to take out of the shell, pod, etc.; as, to shell nuts or pease; to shell oysters.-to separate the kernels of (an ear of indian corn, wheat, oats, etc.) from the cob, ear, or husk.-to throw shells or bombs upon or into; to bombard; as, to shell a town.-to fall off, as a shell, crust, etc.-to cast the shell, or exterior covering; to fall out of the pod or husk; as, nuts shell in falling.-to be disengaged from the ear or husk; as, wheat or rye shells in reaping.