/ Dictionary / Index N neencephalon: Meaning and Definition of Find definitions for: ne•en•ceph•a•lon Pronunciation: (nē"en-sef'u-lon", -lun), [key] — pl. -lons, -la the more recent part of the brain in the evolutionary development of animals, including the cerebral cortex and its related structures. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: neencephalon (Thesaurus) Neenah neep Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language