An Etymological Dictionary of Astronomy and Astrophysics

A → conjunction word used to indicate alternatives.

Etymology (EN): M.E., from or, adverb “early, before,” from Old Norse ār akin to O.E. ær “early.”

Etymology (PE): Yâ, from Mid.Pers. ayâb, aviâp “or;” cf. P.Pers. ada, Av. adā, aδa “then.”