one-horse . one-horse {adj. phr.} Insignificant; modest; provincial. Arnold's business is a one-horse operation; he never had a single employee. Categories: add yours business {adj. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: O Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Comment on this entry