Meaning : Someone who takes the place of another (as when things get dangerous or difficult).
Example :
The star had a stand-in for dangerous scenes.
We need extra employees for summer fill-ins.
Synonyms : backup, backup man, fill-in, relief, stand-in, substitute
Meaning : A pitcher who does not start the game.
Synonyms : fireman, relief pitcher
Reliever meaning in Bengali (Bangla).