1. In the place or area where one is locally established; on one's home turf. The team will be playing the championship match on their own ground this weekend, which they're hoping will give them a bit of an advantage. We'll be hosting the state-wide high school science fair on our own ground next month.

2. In a field, profession, or area for which one has a deep affinity or familiarity. After a string of unsuccessful action films, the director is back on her own ground with a biting new historical drama. I tried a few television roles, but I'm really only on my own ground when I'm doing stand-up.