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Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: The phenomenon by which the Late Proto-Slavic "liquid diphthongs", formed from a vowel followed by a liquid *r or *l, become disyllabic -oro-, -ere- and -olo- reflexes in East Slavic languages. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.