Just say on-prem. Problem solved! Really though, "self-hosted" would make even more sense, as companies often deploy such applications in one or more "off prem

Just say on-prem. Problem solved! Really though, "self-hosted" would make even more sense, as companies often deploy such applications in one or more "off prem" environments anyway. I'd hardly consider my company's multi-region/multi-AZ AWS VPC to be my "premise".