protection has 8 distinct synonyms spread across 6 of its 7 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 activity of protecting someone or something
“the witnesses demanded police protection”
a covering that is intend to protect from damage or injury
“they had no protection from the fallout”
defense against financial failure; financial independence
“his pension gave him security in his old age”
the condition of being protected
“they were huddled together for protection”
kindly endorsement and guidance
“the tournament was held under the auspices of the city council”
the imposition of duties or quotas on imports in order to protect domestic industry against foreign competition
“he made trade protection a plank in the party platform”
Synonyms, antonyms and the broader and narrower relations for protection come from Princeton University’s WordNet. Full sources and licences.