/ Dictionary / Index D double-nickel: Meaning and Definition of Find definitions for: dou•ble-nick•el Pronunciation: (dub'ul-nik'ul), [key] — n. Slang. the national speed limit of 55 miles per hour as established in 1974 on U.S. highways. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. doubleness double-O Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language