on the double! . on the double! {adv. phr.} Hurry up! "Let's go! On the double!" the pilot cried, as he started up the engine of the small plane. Categories: add yours {adv. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: O Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Discuss