A part of the earth's surface
He breached her comfort zone in a way that left her shaken, scared.
He just slid into the zone when his phone rang.
It comprises a comparatively narrow coastal zone, a high inland plateau, and an intermediate zone formed by the terraces and slopes between the two.
It looked like a war zone and smelled like a cesspool.
He stopped in her personal zone, too close, but she wasn't about to back down this time.