Which term is used to describe a lucid state of robust equanimity or tranquility?

little b, since the question is not in normal speech, the answer won't be either.

I'm not good at ataraxia

Arohanui, I want it also!!!

ataraxia: yep, some "Benz" do the trick better than others... (but, usual caveat applies - don't try this at home folks, or at least if you have one: Some of we don't).

Arohanui, Try Yoga!