hard-and-fast . hard-and-fast {adj.} Not to be broken or changed; fixed; strict. The teacher said that there was a hard-and-fast rule against smoking in the school. Categories: add yours {adj.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: H Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Discuss