/ Dictionary / Index P perineurium: Meaning and Definition of Find definitions for: per•i•neu•ri•um Pronunciation: (per"u-noor'ē-um, -nyoor'-), [key] — pl. -neu•ri•a the sheath of connective tissue that encloses a bundle of nerve fibers. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: perineurium (Thesaurus) perineum perinuclear Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language