/ Dictionary / Index S Selective Service System: Meaning and Definition of Find definitions for: Selec'tive Serv'ice Sys"tem Pronunciation: [key] the U.S. federal agency that facilitates the mobilization of military forces by requiring the registration of males between the ages of 18 and 26 years. Abbr.: SSS Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. selective service selective transmission Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language