RichThesaurus
couldn't-care-less
vs
nonchalant
couldn't-care-less
nonchalant
adj
Indifferent; unconcerned; behaving as if detached.
Casually calm and relaxed.
How often have the words
couldn't-care-less
and
nonchalant
occurred in a corpus of books?
(source:
Google Ngram Viewer
)