The oxford that says this?

Acronym

1. A group of initial letters used as an abbreviation for a name or expression, each letter or part being pronounced separately; an initialism

or the merriam webster that says this?

Some people feel strongly that acronym should only be used for terms like NATO, which is pronounced as a single word, and that initialism should be used if the individual letters are all pronounced distinctly, as with FBI. Our research shows that acronym is commonly used to refer to both types of abbreviations.

funny how well this fits for both meanings