surrender has 8 distinct synonyms spread across 5 of its 6 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. Its one recorded opposite is resist.
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 delivery of a principal into lawful custody
the act of surrendering (usually under agreed conditions)
“they were protected until the capitulation of the fort”
Synonyms, antonyms and the broader and narrower relations for surrender come from Princeton University’s WordNet. Full sources and licences.