An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

Math.: A relationship bewteen two quantities such that if one quantity changes the other changes in the same proportion; denoted as y ∝ x.

→ proportional + → -ity.

Math.: A → constant that converts a proportionality into an → equation. Thus the proportionality constant k converts the proportionality y ∝ x into the equation y = kx.

→ proportionality + → constant.