Anything provided as a substitute; a makeshift.
An expression of remorse or regret for having said or done something that harmed another: an instance of apologizing (saying that one is sorry).
A formal justification, defence.
A person who is not good enough to be considered proficient but may be useful as a backup.
A person who plays second string. A person who is kept on a sports team as a backup in case a "first-string" player is unavailable.