best man . best man {n.} The groom's aid (usually his best friend or a relative) at a wedding. When Agnes and I got married, my brother Gordon was my best man. Categories: add yours friends {n.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: B Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Discuss