behind somebody’s back

behind Preposition

— When something is behind a second thing, the first thing is in back of the second. The ball is behind the box. — When something is behind, it is toward the rear. The man stayed behind. — A thing is behind when it happened in the past. We left that worry behind.

behind Noun

— The rear, back-end. — Bottom, downside. — Your behind is your butt, the buttocks, or bum. He was told he would get a kick on the behind if he kept being naughty — In Australian Rules Football, a behind is the same as one point, scored if the ball goes between the tall goal post and the short behind post. He tried to kick a goal, but the ball went wide and he only got a behind.

back Preposition

— Toward the rear. He went back behind the stands. — To a place again. I didn't like it, so I sent it back. He went back to the same house. They came back again.

back Noun

— The back is the rear part of something; it is the part in the other direction from the front. I went to the back of the house. — The back is the rear part of the human body. He had a scar on his back.

back Verb

— If you back something, you support it. The Republicans backed the bill. — If you back up, you move backward. He put the car in gear and backed right into the garage door.