substitute - alternative - surrogate - backup - stand-in - proxy - reserve, - fill-in - replacement - understudy - deputy
Replacement refers to the act of replacing one thing with another. It is a process where something that is lost, broken, or no longer functional is substituted with another item that serves the same purpose or function. Replacements can occur in various contexts, such as replacing a broken component in a machine, substituting a player in a sports team, or exchanging a product in a store for a different item. The concept of replacement encompasses both the act of replacing as well as the new item that takes the place of the original one.