relief has 22 distinct synonyms spread across 8 of its 11 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the feeling that comes when something burdensome is removed or reduced
“as he heard the news he was suddenly flooded with relief”
(law) redress awarded by a court
“was the relief supposed to be protection from future harm or compensation for past injury?”
someone who takes the place of another (as when things get dangerous or difficult)
“the star had a stand-in for dangerous scenes”
assistance in time of difficulty
“the contributions provided some relief for the victims”
a pause for relaxation
“people actually accomplish more when they take time for short rests”
aid for the aged or indigent or handicapped
“he has been on relief for many years”
the act of reducing something unpleasant (as pain or annoyance)
“he asked the nurse for relief from the constant pain”
sculpture consisting of shapes carved on a surface so as to stand out from the surrounding background
the act of freeing a city or town that has been besieged
“he asked for troops for the relief of Atlanta”
Synonyms, antonyms and the broader and narrower relations for relief come from Princeton University’s WordNet. Full sources and licences.