could care less

Etymology
An alteration of (which is first attested slightly earlier), either:


 * by deliberate irony, or
 * by hyponegation, perhaps influenced by forms such as “as if I could care less”, “no one could care less”, and “to know little (or nothing) and care less”.

Verb

 * 1)  To not care at all; to have no concern or interest; to be apathetic.

Usage notes

 * Some consider this expression erroneous because the literal meaning of this version is the opposite of the intended meaning. Others consider it acceptable because it is widespread and because omission of is an instance of Jespersen’s Cycle, a linguistic process attested elsewhere in English and in other languages.