/ Dictionary / Index I Internal Revenue Service: Meaning and Definition of Find definitions for: Inter'nal Rev'enue Serv"ice Pronunciation: [key] the division of the U.S. Department of the Treasury that collects internal revenue, including income taxes and excise taxes, and that enforces revenue laws. Formerly, Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. internal revenue internal rhyme Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language