Huh, well that's my new thing I've learned today. I only ever heard it in conjunction with curry-type things (katsu chicken, which was always served with curry, for instance).
As in a small "cut of chicken" is a "chicken cutlet?"
It originally referred to the same thing "chop" does today, a slice of meat perpendicular to the spine, containing a single rib. Then it started referring specifically to a boneless chop. Then it started being used to refer to any thin slice of meat. And in a lot of the world it was introduced specifically as a breaded and fried thin slice of meat. And that's how we got katsu, the Japanese version of schnitzel.
Language is weird, isn't it?