former has 10 distinct synonyms spread across 3 of its 5 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 latter.
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.
referring to the first of two things or persons mentioned (or the earlier one or ones of several)
“the novel was made into a film in 1943 and again in 1967; I prefer the former version to the latter one”
Synonyms, antonyms and the broader and narrower relations for former come from Princeton University’s WordNet. Full sources and licences.