A lot of superhero role-playing products call superheroes ‘supers’.
This seems to be because DC and Marvel jointly claim a trademark on the phrase ‘Super Hero’.
That claim seems to this non-lawyer to be pretty far-fetched (a bit like McDonalds and Burger King claiming to own the word ‘burgers’). But that’s not the point. The point is this:
No one calls them ‘supers’.
No one. Not ever. Not even the role-playing designers who use the term in their products. The term doesn’t even appear in the Wikipedia article on superheroes.
EDIT: I was wrong. Apparently The Incredibles did. Still, that movie doesn’t seem to have brought the term ‘supers’ into common use outside of RPGs. It seems more likely to me that RPG creators’ main motivation in using ‘supers’ is fear of being sued, rather than wanting to use the term that The Incredibles used or that they usually say ‘supers’ rather than ‘super heroes’.
It makes me think of spam that I used to get trying to sell me ‘meds’.
Game designers, if you’re terrified of Marvel and DC, make up something like ‘science hero‘, which has its own retro charm.
PS Superheroes superheroes superheroes superheroes.