mantle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A loose sleeveless coat worn over outer garments; a cloak.
• noun Something that covers, envelops, or conceals.
• noun The role or appearance of an authoritative or important person.
• noun The outer covering of a wall.
• noun A zone of hot gases around a flame.
• noun A device in gas lamps consisting of a sheath of threads that gives off brilliant illumination when heated by the flame.
• noun Anatomy The cerebral cortex.
• noun Geology The zone of the earth between the crust and the core.
• noun The outer wall and casing of a blast furnace above the hearth.
• noun The shoulder feathers, upper back, and sometimes the wings of a bird when differently colored from the rest of the body.
• noun A fold or pair of folds of the body wall that covers the internal organs and typically secretes the substance that forms the shell in mollusks and brachiopods.
• noun The soft outer wall lining the shell of a tunicate or barnacle.
• intransitive verb To cover with a mantle.
• intransitive verb To cover with something that acts like a mantle; cover, envelop, or conceal.
• intransitive verb To spread or become extended over a surface.
• intransitive verb To become covered with a coating, as scum or froth on the surface of a liquid.
• intransitive verb To blush.

from The Century Dictionary.

• To cover with or as if with a mantle; disguise; obscure or protect by covering up.
• Specifically—2. In the manufacture of alum from aluminous shales or alum ores, to cover (a partly or completely calcined heap of the ore) with a layer of previously calcined ore.
• To expand and spread; serve as a mantle or covering.
• To become covered with a coating, as a barmy liquid; send up froth or scum; cream, or cream over; foam.
• To be or become overspread or suffused, as with blushes or color; hence, to display a superficial change of hue or of expression.
• In falconry, to stretch out one wing after the leg, as a hawk, by way of relief; spread out the wings for ease: sometimes used figuratively.
• noun A loose sleeveless garment worn as an outer covering, falling in straight lines from the shoulders; a simple kind of cloak.
• noun Figuratively, a cover or covering; something that conceals.
• noun Specifically— An outer covering of a wall, differing in material from the inner part.
• noun In founding, a covering of porous clay laid over a pattern in wax. When heat is applied the wax melts and runs out, leaving the clay mantle in condition to serve as a mold.
• noun The outer enveloping masonry of a blast-furnace.
• noun In zoology and anatomy, some part or organ which covers, conceals, or mantles: In Mollusca, the pallium. In Cirripedia, the sac, formed by the dorsal part of the integument, which incloses the body. In ornithology, the pallium or stragulum. See stragulum. The tunic of an ascidian.
• noun In heraldry, same as mantling, 3.
• noun An inclosed chute which leads water from a fore-bay to a water-wheel.
• noun In the incandescent gas-light of Dr. Auer von Weisbach, a tube variously composed of one or more of the oxids of zirconium, lanthanum, thorium, and cerium, and prepared by dipping a tube of cotton netting (made by a knitting-machine) into a solution, or mixed solutions, of the oxid or oxids, thus coating the filaments, which after coating are burned out, leaving a consolidated tube.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To cover or envelop, as with a mantle; to cloak; to hide; to disguise.
• noun A loose garment to be worn over other garments; an enveloping robe; a cloak.
• noun (Her.) Same as Mantling.
• noun The external fold, or folds, of the soft, exterior membrane of the body of a mollusk. It usually forms a cavity inclosing the gills. See Illusts. of Buccinum, and Byssus.
• noun Any free, outer membrane.
• noun The back of a bird together with the folded wings.
• noun (Arch.) A mantel. See Mantel.
• noun The outer wall and casing of a blast furnace, above the hearth.
• noun (Hydraulic Engin.) A penstock for a water wheel.
• noun (Geol.) The highly viscous shell of hot semisolid rock, about 1800 miles thick, lying under the crust of the Earth and above the core. Also, by analogy, a similar shell on any other planet.
• intransitive verb To unfold and spread out the wings, like a mantle; -- said of hawks. Also used figuratively.
• intransitive verb To spread out; -- said of wings.
• intransitive verb To spread over the surface as a covering; to overspread.
• intransitive verb To gather, assume, or take on, a covering, as froth, scum, etc.