swapsystem

2. A computer setup that lets data be moved between memory and storage when space runs low.

The old computer used a swapsystem to keep running when its memory was full.

3. An arrangement where two people or groups take turns doing something for each other.

The neighbors set up a swapsystem for walking each other's dogs.

4. A method in which players trade items or cards in a game.

The card game has a swapsystem so players can trade duplicates.