An Etymological Dictionary of Astronomy and Astrophysics

Proceeding, taking place, changing by small degrees.

Etymology (EN): From M.L. gradualis, from L. gradus “step.”

Etymology (PE): Padâkvâr, from padâk “grade,” + -vâr a suffix which denotes “suiting, befitting, resembling, in the manner of, possession.”
Pâypâyé “step by step,” from pây, pâ “foot, step,” → foot.