An Etymological Dictionary of Astronomy and Astrophysics

A Gk. prefix denoting “under.”

Etymology (EN): Gk. hypo “under” (prep.), “below” (adv.); cognate with L. sub- and
O.Pers./Av. upā, as below.

Etymology (PE): Upâ-, from O.Pers. upā (prep.) “under, with;” Av. upā, upa (prep.; prevb) “toward, with, on, in” (upā.gam- “to arrive at,” upāpa- “living in the water,” upa.naxturušu “bordering on the night”); Mod.Pers. bâ “with,” from abâ; cf. Skt. úpa (adv., prevb., prep.) “toward, with, under, on;” cognate with Gk. hypo, as above.