cooperating; acting together to produce an effect.-that which unites in action with something else to produce the same effect.-a number or letter put before a letter or quantity, known or unknown, to show how many times the latter is to be taken; as, 6x; bx; here 6 and b are coefficients of x.-a number, commonly used in computation as a factor, expressing the amount of some change or effect under certain fixed conditions as to temperature, length, volume, etc.; as, the coefficient of expansion; the coefficient of friction.