gripper

noun

1. a person or thing that grips something

2. a cover on the handle of a bicycle, tool, etc, that makes it easier to grip.

3. (curling) A rubber or other material attached to a curling shoe to improve traction on the ice

4. (rail transport, slang) a ticket collector

5. (computing, graphical user interface) A visual component on a window etc. enabling it to be resized and/or moved.