Second-string and Backup

second-string

Being a replacement or substitute for a regular member of a team.
- usage: "a second-string pitcher"

backup

An accumulation caused by clogging or a stoppage.
- usage: "a traffic backup on the main street"; "he discovered a backup in the toilet"
Someone who takes the place of another (as when things get dangerous or difficult. )
- usage: "the star had a stand-in for dangerous scenes"; "we need extra employees for summer fill-ins"
- synonyms: stand-in, substitute, relief, reliever, backup man, fill-in
A musical part (vocal or instrumental) that supports or provides background for other musical parts.
- synonyms: accompaniment, musical accompaniment, support
Computer science. ( a copy of a file or directory on a separate storage device)
- usage: "he made a backup in case the original was accidentally damaged or erased"
- synonyms: computer backup
The act of providing approval and support.
- usage: "his vigorous backing of the conservatives got him in trouble with progressives"
- synonyms: backing, championship, patronage