An Etymological Dictionary of Astronomy and Astrophysics

The first daylight in the sky before sunrise, equivalent to morning astronomical → twilight; opposed to → dusk.

Etymology (EN): M.E. dawen (v.), from O.E. dagung, from dagian “to become day,” from root of dæg→ day.

Etymology (PE): Pegâh, from Mid.Pers. pa gâh, literally “soon; near the time (of sunrise),” from pa “to; for; in; on; with; by; according to,” O.Pers. upā, Av. upa “toward, with, on, in, in the time of” (cf. Skt. úpa “toward, together with, under, near to, on,” Gk. hypo “under, below,” L. sub “under,” Ger. auf, E. up; PIE *upo “under, up from under, over”) + gâh “time,” O.Pers. gāθu-, Av. gātav-, gātu- “place, throne, spot” (Skt. gátu- “going, motion; free space for moving; place of abode,” PIE *gwem- “to go, come”).
Sepidedam, from sepidé “whitish; dawn,” from sepid “white” (Mid.Pers. spêt, Av. spita- “white,” Skt. śveta- “white,” Lith. sviesti “to shine,” svaityti “to brighten,” P.Gmc. *khwitaz, O.E. hwit, E. white, Ger. weiss, PIE *kwintos/*kwindos “bright”) + dam “moment, time; to blow, breathe; smoke” (Mod./Mid.Pers. damidan “to blow, breathe,” Av. dāδmainya- “blowing up,”
Skt. dahm- “to blow,” dhámati “blows,” Gk. themeros “austere, dark-looking,” Lith. dumti “to blow,” PIE dhem-/dhemə- “to smoke, to blow”).
Bâmdâd, from Mid.Pers. bâmdât, Av. bāmya- “the dawn,” from bā- “to shine” (cf. Skt. bhā- “light, brightness,” Gk. phainomai “to appear, shine, gleam,” Arm. banam “to open, uncover,” PIE *bhā- “to shine”).