/ Dictionary / Index E epitrichium: Meaning and Definition of Find definitions for: ep•i•trich•i•um Pronunciation: (ep"i-trik'ē-um), [key] — pl. -ums. the outermost layer of the epidermis in most mammalian fetuses, usually disappearing before birth. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. epitrachelion epitrochoid Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language