Spacer (noun)

1. A device or piece of material that is used to separate or keep apart two things.
2. A person or thing that creates or maintains a space or gap between other things.

Origin:

From space + -er.

Examples:

1. The spacer in the door helped to keep it from sticking.
2. The spacer in the bridge helps to distribute the weight evenly.
3. The spacers are used to ensure proper spacing between the tiles.
4. The spacer on the bike helps to maintain the distance between the handlebars and seat.
5. The spacer in the engine helps to maintain the proper clearance for the pistons.