The tag alias #70511 gymnasium -> gym is pending approval.
Reason: I checked, and Gym is just short for Gymnasium. There is no reason to have both of these tags.
Topic: Tag alias: gymnasium -> gym
Posted under Tag Alias and Implication Suggestions
Well not "just" gym: https://en.wikipedia.org/wiki/Gymnasium_(school))
But posts currently and previously tagged as gymnasium only seem to have gyms, so I'd say it's good enough.