replacement

noun

1. the act of furnishing an equivalent person or thing in the place of another"replacing the star will not be easy"
2. someone who takes the place of another person
3. an event in which one thing is substituted for another"the replacement of lost blood by a transfusion of donor blood"
4. a person or thing that takes or can take the place of another
5. filling again by supplying what has been used up
6. a person who follows next in order"he was President Lincoln's successor"