Replacement (noun)

1. The action or process of replacing something or someone.
2. A person or thing that takes the place of another.
3. A spare part or component that is used to replace a damaged or defective one.

Origin:

Late 19th century: from replace + -ment.

Examples:

1. He was told that he was being replaced as manager.
2. The company's replacement product was not as good as the original.
3. The replacement parts for the car were expensive.
4. The team is looking for a replacement player.
5. The replacement of the old system with a new one was difficult.