having due proportion; corresponding.

being in or characterized by proportion.

of, pertaining to, or based on proportion; relative.

Mathematics .

(of two quantities) having the same or a constant ratio or relation

The quantities y and x are proportional if y/x k, where k is the constant of proportionality.

(of a first quantity with respect to a second quantity) a constant multiple of

The quantity y is proportional to x if y kx, where k is the constant of proportionality.