Coefficient

n.
  1. That which unites in action with something else to produce the same effect.
  2. (Math.) 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.
  3. (Physics) 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.
    4. Arbitrary coefficient (Math.),
    a literal coefficient placed arbitrarily in an algebraic expression, the value of the coefficient being afterwards determined by the conditions of the problem.