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

A flow in which the characterizing conditions, such as → streamlines or velocity at any given point, do not change with time.

→ steady; → flow.

Tacân, → flow; pâyâ "steady, constant," from pâyidan "to stand firm, to be constant, steady," from Mid.Pers. pattây-, pattutan "to last, endure, stay."