combination has 2 distinct synonyms spread across 1 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.
a collection of things that have been combined; an assemblage of separate parts or qualities
a coordinated sequence of chess moves
Synonyms, antonyms and the broader and narrower relations for combination come from Princeton University’s WordNet. Full sources and licences.
a sequence of numbers or letters that opens a combination lock
“he forgot the combination to the safe”
a group of people (often temporary) having a common purpose
“they were a winning combination”
an alliance of people or corporations or countries for a special purpose (formerly to achieve some antisocial end but now for general political or economic purposes)
the act of arranging elements into specified groups without regard to order
the act of combining things to form a new whole