/ Dictionary / Index P paleencephalon: Meaning and Definition of Find definitions for: pa•le•en•ceph•a•lon Pronunciation: (pā"lē-en-sef'u-lon" esp. Brit. pal"ē-), [key] — pl. -la (no longer in technical use) the more primitive part of the brain in the evolutionary development of animals, including all parts except the cerebral cortex and its related structures. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: paleencephalon (Thesaurus) pale-dry paleethnology Related Content Daily Word Quiz: jovial Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language