||Ra`bat" (?), n. [F. Cf. Rabato.] (Eccl.) (a) A clerical linen collar. (b) A kind of clerical scarf fitted to a collar; as, a black silk rabat.
Race"a*bout` (?), n. (Naut.) A small sloop-rigged racing yacht carrying about six hundred square feet of sail, distinguished from a knockabout by having a short bowsprit.
Race suicide. The voluntary failure of the members of a race or people to have a number of children sufficient to keep the birth rate equal to the death rate.
Rack"a*rock` (?), n. [Rack to stretch, strain + a + rock.] A Sprengel explosive consisting of potassium chlorate and mono-nitrobenzene.
Rack"et, n. A scheme, dodge, trick, or the like; something taking place considered as exciting, trying, unusual, or the like; also, such occurrence considered as an ordeal; as, to work a racket; to stand upon the racket. [Slang]
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Radial engine. (Mach.) An engine, usually an internal-combustion engine of a certain type (the radial type) having several cylinders arranged radially like the spokes of a complete wheel. The semiradial engine has radiating cylinders on only one side of the crank shaft.
Ra"di*ant (?), a. (Physics) Emitted or transmitted by radiation; as, a radiant energy; radiant heat.
Radiant engine. (Mach.) A semiradial engine. See Radial engine, above.
Ra"di*a`tor (?), n. 1. Any of various devices for cooling an internal substance by radiation, as a system og rings on a gun barrel for cooling it, or a nest of tubes with large radiating surface for cooling circulating water, as in an automobile.