run its course . run its course {v. phr.} To fulfill a normal development; terminate a normal period. Your flu will run its course; in a few days you'll be back on your feet. Categories: add yours {v. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: R Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Comment on this entry