An Etymological Dictionary of Astronomy and Astrophysics

To control, direct, or adjust by a rule, principle, method, etc.

Etymology (EN): From L.L. regulatus, p.p. of regulare “to control by rule, direct,” from L. regula, cognate with Pers. râst→ right.

Etymology (PE): Razanidan, verbal form of razan, → rule, cognate with L. regula.