In this paper, we essay a generalization of the classical concept of growth order of an entire function. We define the new parameter ρg(f), the relative growth order of f(z) with respect to g(z), which establishes a direct comparison between the growth of the moduli of two nonconstant entire functions f and g. Diverse properties, relative to sum, product, composition, derivative, real and imaginary parts, Nevanlinna’s characteristic and Taylor’s coefficients are studied.