/ Dictionary / Index P prosencephalon: Meaning and Definition of Find definitions for: pros•en•ceph•a•lon Pronunciation: (pros"en-sef'u-lon", -lun), [key] — pl. -las, -la the forebrain. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: prosencephalon (Thesaurus) proseminar prosenchyma Related Content Daily Word Quiz: ostracize Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language