Polnoglasie is a synonym of pleophony.

In linguistics|lang=en terms the difference between polnoglasie and pleophony

is that polnoglasie is (linguistics) the phenomena of a disyllabic -oro-, -ere- and -olo- reflexes in east slavic languages of late proto-slavic closed syllable clusters involving a vowel *a, *o, *e followed by a liquid *r or *l while pleophony is (linguistics) 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.

As nouns the difference between polnoglasie and pleophony

is that polnoglasie is (linguistics) the phenomena of a disyllabic -oro-, -ere- and -olo- reflexes in east slavic languages of late proto-slavic closed syllable clusters involving a vowel *a, *o, *e followed by a liquid *r or *l while pleophony is (linguistics) 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.