What is Karuṇā? Is 'compassion' really a good translation?

Is compassion really a good translation for *Karuna*? I've been fooled by "patience " before, now I'm sort of suspicious of the other common translations for the paramitas. Does karuna in addition to feeling other people's pain also entail regret? In "A Few Good Men" by Nattier, she talks about people on the Bodhisattva path developing karuna by doing a 3 part ritual that is a repentance ritual. This seems far removed from imaginatively feeling the pain of others. Could it be that Karuna and English compassion, don't cover the same semantic ground?