An Etymological Dictionary of Astronomy and Astrophysics

A combining form meaning “turn, change.”

Etymology (EN): From Gk. tropos “turn,” trope “a turning,” from trepein “to turn;” cognate with Pers. sabok and zab, → trivial.

Etymology (PE): Gašt “turning,” past stem of gaštan, gardidan “to turn, to change” (Mid.Pers. vartitan; Av. varət- “to turn, revolve;” Skt. vrt- “to turn, roll,” vartate “it turns round, rolls;” L. vertere “to turn;” O.H.G. werden “to become;” PIE base *wer- “to turn, bend”).