Well for what it's worth I've been published on a fair number of aspects of flight mechanics, and studied it to TPS and PhD level.
For my money there is sideslip (also known as "Beta"). "Skid", "forward slip", and any other bits of terminology are just complicating an issue that doesn't require it.
Incidentally, you really shouldn't teach constant IAS in a sideslip, you should teach constant attitude. Constant IAS + blocked static on one side = either too fast + rudder (risk of structural damage) or too slow + rudder (risk of spin).
G