back of one's mind

• back of one's head

back of one's mind

1. One's remote memory.
   • 2020 August 26, Tim Dunn, “Great railway bores of our time!”, in Rail, page 44:

     So much of what followed from the drawing boards of others will have been designed with the demands, effort and grandeur of Primrose Hill [tunnel] in the back of their minds.

2. The supposed location of low-importance plans within the brain.
   • 2008, Major General John Frost, A Drop Too Many‎:

     In the backs of all our minds was the proud hope that somehow or other we should get there.

   Wallpapering the bedroom has been at the back of my mind for some time now.

• “the back of one’s mind”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.