An Etymological Dictionary of Astronomy and Astrophysics

Math.: A succession of numbers or quantities in which there is a constant relation between each member and the one succeeding it. See also → arithmetic progression, → geometric progression, → harmonic progression.

Etymology (EN): From O.Fr. progression, from L. progressionem “a going forward,” from progressus, p.p. of progredi “go forward,” from → pro- “forward” + gradi “to step, walk,” from gradus “step.”

Etymology (PE): Farâyâzi, from farâ-, → pro-, + yâzi, verbal noun of yâzidan “to stretch out the arms; grow up;” Parthian Mid.Pers. y’d “to reach a goal, come to, stretch out;” Av. yat- to reach, take one’s place," yaiiata “places,’ frā-iiatāt “has reached;” cf. Skt. yat- “to be in place, put in place, line up;” PIE base *iet- “to be in place.”