ὀ

German (Pape)

[Seite 284] ὀ- praefixum, = ὁμο-, s. ὀπάτριος.

Russian (Dvoretsky)

ὀ: приставка:
1 ὀ- copulativum, со смыслом совместности, (напр., ὄπατρος происходящий от того же отца);
2 ὀ- protheticum, чисто фонетического значения (напр., ὀκέλλω наряду с κέλλω).

Frisk Etymological English

1. Meaning: copulative prefix in ὄ-πατρος with the same paternal descent (Λ 257, Μ 371; ὀπάτριος Lyc.; cf. s.v.); ὄ-τριχες ἵπποι horses with comparable manes (Β 765); ὀγάστωρ ὁμογάστωρ, ὄζυγες ὁμόζυγες H. u.a., also in οἰέτεας (s.v.).
Origin: IE [Indo-European] [902] *sem- one
Etymology: Prob. Aeolic for ἀ-, ἁ- copulativum; s.v. and Schwyzer 433 w. lit. Semantically it comes oftn close to the next (ὀ- 2).
2. Meaning: near to, by, to, with fixed prefix assumed in ὀ-κέλλω to drive on shore, prob. also in ὀτρύνω, ὄζος, ὄσχος, ὄψον; further see under the separate words; cf. also ὄαρ. It is very rare, and doubtful.
Origin: XX [etym. unknown]
Etymology: Without direct agreement outside Greek. A similar function has Indo-Iran. (preverb and prep.) ā- at it, towards, from ... away (e.g. Skt. ā-gam- arrive, come towards); further, more or less uncertain cases from other languages in WP. 1, 95f., Pok. 280f. Forms with long vowel have been supposed with doubtful right in ὠρύομαι, ἠβαιός, ἠρέμα, s. vv. (note that two of these words would have ἠ-) and Schwyzer 434, Schw.-Debrunner 491. Not here ἐθέλω (s.v.; through aphaeresis θέλω); ὠκεανός is Pre-Greek.