/ Dictionary / Index A additament: Meaning and Definition of Find definitions for: ad•dit•a•ment Pronunciation: (u-dit'u-munt), [key] — n. something added; an addition. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Addison's disease addition Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language