The back (of the body) — the rear part of the torso from the shoulders down to the waist.
背中が痛いので整体に行った。
My back hurt, so I went to a chiropractor.
彼女は背中に大きなリュックを背負っていた。
She was carrying a large backpack on her back.
背中を向けて話さないでください。こちらを見てください。
Please don't talk with your back turned. Look this way.