shifter

noun

1. 1.One who, or that which, shifts or changes.
2. 2.A word whose meaning changes depending on the situation, as by deixis.
3. 3.One who plays tricks or practices artifice; a cozener.
4. 4.An assistant to the ship's cook in washing, steeping, and shifting the salt provisions.
5. 5.An arrangement for shifting a belt sidewise from one pulley to another.