Coöperating; acting in union to the same end.n. That which unites in action with something else to produce a given effect; that which unites its action with the action of another.n. In algebra, a number or other constant placed before and multiplying an unknown quantity or variable or an expression containing such quantities; also, a number multiplying a constant or known quantity expressed algebraically—that is, by the letters a, b, etc.n. In physical, a numerical quantity, constant for a given substance, and used to measure some one of its properties: as, the coefficient of expansion of any substance is the amount which the unit of length (surface or volume) expands in passing from 0° to 1° C.n. Same as coefficient of variation.n. Superior lethal coefficient, that medium concentration of a disinfectant which will kill bacteria spores in water at a temperature of 20–25° C. in the shortest time.n. The coefficient of change in electrical resistance of a substance with variation of temperature. The temperature coefficient is given by the equation: in which r is the resistance of the substance at the temperature to, and ro, its resistance at 0°.