series has 2 distinct synonyms spread across 2 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.
Synonyms, antonyms and the broader and narrower relations for series come from Princeton University’s WordNet. Full sources and licences.
a serialized set of programs
“a comedy series”
(sports) several contests played successively by the same teams
“the visiting team swept the series”
(electronics) connection of components in such a manner that current flows first through one and then through the other
“the voltage divider consisted of a series of fixed resistors”
a group of postage stamps having a common theme or a group of coins or currency selected as a group for study or collection
“the Post Office issued a series commemorating famous American entertainers”
(mathematics) the sum of a finite or infinite sequence of expressions