Stationary means a blackhole that is not evolving in time---one that is in a stationary state https://en.wikipedia.org/wiki/Stationary_state https://en.wikiped

Stationary means a blackhole that is not evolving in time---one that is in a stationary state https://en.wikipedia.org/wiki/Stationary_state https://en.wikipedia.org/wiki/Stationary_state Note that the article focuses on the QM meaning of stationary, but there's a perfectly good classical analogue: something which is not evolving in time. That doesn't mean that the BH can't spin, it's that the mass, charge, angular momentum isn't changing.