/ Dictionary / Index A addn.: Meaning and Definition of Find definitions for: addn. Pronunciation: [key] addition. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. addlepated addnl. Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language