n. (pl. moduli) Math. 1 a the magnitude of a real number without regard to its sign. b the positive square root of the sum of the squares of the real and imaginary parts of a complex number. 2 a constant factor or ratio. 3 (in number theory) a number used as a divisor for considering numbers in sets giving the same remainder when divided by it. 4 a constant indicating the relation between a physical effect and the force producing it.
[ L, = measure, dimin. of modus ]