An Etymological Dictionary of Astronomy and Astrophysics

Adverb, used as prefix denoting “in, into, onto; toward; with continuous activity,” etc.

Etymology (EN): O.E. on, variant of an “in, on, into,” from P.Gmc. (cf. Du. aan, Ger. an, Goth. ana “on, upon”), from PIE base *ano “on” (cf. Av. ana “on,” Gk. ana “on, upon,” L. an-, O.C.S. na, Lith. nuo “down from”).

Etymology (PE): Bar “on; up; upon; in; into; at; forth; with; near; before; according to” (Mid.Pers. abar; O.Pers. upariy “above; over, upon, according to;” Av. upairi “above, over,” upairi.zəma- “located above the earth;” cf. Gk. hyper- “over, above;” L. super-; O.H.G. ubir “over;” PIE base *uper “over”).
Dar- “in,” from Mid.Pers. andar, → intra-.