fasten on . fasten on {v. phr.} To attach; tie something to make it secure. "Fasten on your life jackets when you get into the life boats," the captain said. Categories: add yours life {v. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2025 To section: F Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Comment on this entry