/ Dictionary / Index P pileum: Meaning and Definition of Find definitions for: pi•le•um Pronunciation: (pī'lē-um, pil'ē-), [key] — pl. pi•le•a the top of the head of a bird, from the base of the bill to the nape. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. pileous pileup Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language