If you turn something in, you return it to the place or person you borrowed it from. I went back to the station-house to turn in my badge and gun = return
carry out (performances); "They turned in a splendid effort"; "They turned in top jobs for the second straight game"
A pass route in which the receiver runs, downfield for a short distance, then turns toward the middle of the field
go to bed in order to sleep; "I usually turn in at midnight"; "He turns out at the crack of dawn"
to surrender someone or something to another; "the guard delivered the criminal to the police"; "render up the prisoners"; "render the town to the enemy"; "fork over the money"
If you turn someone in, you take them to the police or tell the police where they are because they are suspected of committing a crime. If you turn yourself in, you go to the police because you have been involved in a crime. He has been given until noon today to turn himself in to authorities There would be strong incentives to turn someone in I might today hesitate to turn in a burglar
The part of the covering material on a hard cover book that wraps over the edge of the cover and is pasted down on the inside edge of the cover board The covering material may be paper, cloth, leather or other material The cut edge of the covering material is usually concealed by the paste down end paper
When you turn in a completed piece of work, especially written work, you give it to the person who asked you to do it. Now we wait for them to turn in their essays I want everybody to turn a report in. = hand in