Leonine
Definition: resembling a lion; powerful, majestic, like a lion
This seems to be a compliment used to describe something that embodies all the positive qualities of a lion.
“Leo” is Latin for lion, but I couldn’t find any references to this being used to discuss actual lions. It seems to only be used to relate other things to the qualities of a lion.
Why I Looked It Up
From Eurostorm:
Elise had never seen her leonine brother this vulnerable before.