Therianthrope is a human who can metamorphose into an animal. Also a shapeshifter. Therianthropy is the ability to do that.
What’s fun for me is that this is exactly what my secret society, the Netahs, do. This makes them different from many mythological creatures that are half man or woman and half animal. For instance, the centaur is man/horse, a mermaid is woman/fish, a sphinx is man/lion, and the minotaur is man/bull head.
The Cheyenne word I found that the title of my secret society is based on means to change quickly and be different. Why did I chose this word instead of therianthrope? Because my story takes place in Colorado, and I wanted the name to come from a culture that was here first. Besides, the Therianthropes is such a mouthful!