slip one's mind slip one's mind {v. phr.} To forget something. I meant to mail those letters but it entirely slipped my mind. Categories: add yours {v. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 » In RussianTo section: S Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Comment on this entry