To fasten or attach something with a pin or similar device. She pinned the note to the bulletin board.
To hold someone or something firmly in a particular position so they cannot move. He pinned the opponent to the ground during the wrestling match.
To fix blame or responsibility on someone. They tried to pin the mistake on the new employee.
To cause a computer window or application to remain visible on the screen. You can pin the chat window to the side of your screen for easy access.