/ Dictionary / Index S Sixteenth Amendment: Meaning and Definition of Find definitions for: Six'teenth Amend'ment Pronunciation: [key] an amendment to the U.S. Constitution, ratified in 1913, authorizing Congress to levy a tax on incomes. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sixteenth sixteenth note Related Content Daily Word Quiz: ambidextrous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language