/ Dictionary / Index E eighteenmo: Meaning and Definition of Find definitions for: eight•een•mo Pronunciation: (ā'tēn'mō), [key] — pl. adj. -mos, octodecimo. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. eighteen eighteenth Related Content Daily Word Quiz: acme Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language