turn in

turn in  {v.}

1. or hand in

To give to someone; deliver to someone.

I want you to turn in a good history paper.

When the football season was over, we turned in our uniforms.

2. To inform on; report.

She turned them in to the police for breaking the street light.

3. To give in return for something.

They turned in their old money for new.

We turned our car in on a new model.

Syn.: TRADE IN.

4.  {informal}

To go to bed.

We were tired, so we turned in about nine o'clock.

Contrast: TURN OUT (4).