What does kogas name mean?

it means leader

Riss: Koga, as I've learned, can refer to multiple different meanings. The best I've heard is that it means "old river". However, if spelled "Kouga" with a u separating the o and the g, the meaning could change unbelievably fast to 'steel-fang'. I think it's one of those names where there's not an exact definition in english, you know? ^^ Hope I helped!