slip mind

slip (one's) mind

To be forgotten, especially of an obligation. I'm sorry I didn't call you back sooner, it totally slipped my mind.
See also: mind, slip
Farlex Dictionary of Idioms.

slip one's mind

[for something that was to be remembered] to be forgotten. I meant to go to the grocery store on the way home, but it slipped my mind. My birthday slipped my mind. I guess I wanted to forget it.
See also: mind, slip
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

slip somebody’s ˈmemory/ˈmind

forget about something or forget to do something: I was supposed to go to the dentist today, but it completely slipped my mind.
See also: memory, mind, slip
Farlex Partner Idioms Dictionary
See also:
  • slip (one's) mind
  • slip one's mind
  • slip somebody's memory/mind
  • slip your mind
  • have (one's) mind on other things
  • have your mind on other things
  • to my mind
  • have a mind to
  • have a mind to (do something)
  • have a mind to do something