"reliever" in the noun sense
1. stand-in, substitute, relief, reliever, backup, backup man, fill-in
someone who takes the place of another (as when things get dangerous or difficult
"the star had a stand-in for dangerous scenes"
"we need extra employees for summer fill-ins"
2. reliever, allayer, comforter
a person who reduces the intensity (e.g., of fears) and calms and pacifies
"a reliever of anxiety"
"an allayer of fears"
3. reliever, relief pitcher, fireman
a pitcher who does not start the game
Source: WordNet® (An amazing lexical database of English)
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