didn't care a whit

care a whit

To care just the smallest amount. (A "whit" is an iota.) Often used in the negative. I don't care a whit what the neighbors say, I'm not taking that fence down!
See also: care, whit
Farlex Dictionary of Idioms.

didn't care a whit

 and don't care a whit
didn't care at all. Sally thought Joe liked her, but he didn't care a whit about her. I don't care a whit what you do with my old clothes.
See also: care, whit
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • care a whit
  • whit
  • like I care
  • see if I care
  • See if I care!
  • see what I care
  • SIIC
  • take care of
  • take care of (someone or something)
  • take care of someone