/ Dictionary / Index A apterium: Meaning and Definition of Find definitions for: ap•te•ri•um Pronunciation: (ap-tēr'ē-um), [key] — pl. -te•ri•a one of the featherless portions of the skin of a bird. Cf. pteryla. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. apteral apterous Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language