Definition from Wiktionary, the free dictionary
From earlier prie-, from Proto-Balto-Slavic *prei(ʔ), from Proto-Indo-European *prey. Cognate with Lithuanian priẽ (“at, with, to”), príe- (“at, with, to”), Old Prussian prei (“at, with, to”) and Common Slavic *pri (“at, with, by”).
- Usually found on verbs (and their derived nouns or adjectives) with the meaning "to", "to the front", or "joining", "adding", "in addition" (like Russian при- (pri-)).
- Rick Derksen (2008), Etymological Dictionary of the Slavic Inherited Lexicon, Brill: Leiden-Boston, page 419