An Etymological Dictionary of Astronomy and Astrophysics

Prefix meaning “upon, at, close upon (in space or time), on the occasion of, in addition.”

Etymology (EN): Gk. epi- “upon, at, close upon (in space or time), on the occasion of, in addition,” cognate with O.Pers./Av. apiy-, aipi- “upon, toward, along; also; however;” Skt. api “also, besides.”

Etymology (PE): Prefix api-, from O.Pers./Av. apiy-, aipi-, as above.