chain has 11 distinct synonyms spread across 5 of its 12 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 unchain.
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.
a series of things depending on each other as if linked together
“the chain of command”
(chemistry) a series of linked atoms (generally in an organic molecule)
a series of (usually metal) rings or links fitted into one another to make a flexible ligament
(business) a number of similar establishments (stores or restaurants or banks or hotels or theaters) under one ownership
British biochemist (born in Germany) who isolated and purified penicillin, which had been discovered in 1928 by Sir Alexander Fleming (1906-1979)
a series of hills or mountains
“the valley was between two ranges of hills”
a linked or connected series of objects
“a chain of daisies”
connect or arrange into a chain by linking
fasten or secure with chains
“Chain the chairs together”
Synonyms, antonyms and the broader and narrower relations for chain come from Princeton University’s WordNet. Full sources and licences.