/ Dictionary / Index P perionychium: Meaning and Definition of Find definitions for: per•i•o•nych•i•um Pronunciation: (per"ē-ō-nik'ē-um), [key] — pl. -nych•i•a the epidermis surrounding the base and sides of a fingernail or toenail. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. perionychia periosteum Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language