I used to fly full-scale sailplanes, an activity in which the ability to slip is essential, since with no engine if you miss the runway you can't go around. Back then, we just called them "slips," without distinguishing "forward slips" from "side slips." But that was some years ago.

It is remarkable how much harder it is to do slips with an RC model than with a full-scale aircraft. I'm guessing that this is partly because stick and rudder pedals are easier to work with than two sticks, but that's just a guess.