The word  speed  in the ide is highlighted

As the title says, the word speed is highlighted as a keyword in the ide. Where does this come from?

I have been using speed as a variable name without really noticing the highlight.

It's probably used in one of the libraries (stepper ??).

That is what I thought, but would it still be highlighted if I don't use the library?

I can answer my own post here. Yes it is. If I remove the word from the stepper keyword list then it is no longer highlighted.