Definition of I or he, she, etc. couldn't North American informal also could care less in English:

I (or he, she, etc.) couldn't (North American informal also could) care less

informal Used to express complete indifference: he couldn’t care less about football [as adjective]: I started to get irritated by this couldn’t-care-less attitude
More example sentences
  • Those on the right want more drilling and couldn't care less about conservation.
  • By saying nothing to you about your achievements, it can seem to you as if they couldn't care less.
  • It was good to be in a crowd of people who couldn't care less about blogging for part of the weekend.
See parent entry: care

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Word of the day flagitious
Pronunciation: fləˈdʒɪʃəs
adjective
(of a person or their actions) criminal; villainous