bivalent has 2 distinct synonyms spread across 2 of its 2 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 2 recorded opposites are multivalent, univalent.
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.
having a valence of two or having two valences
used of homologous chromosomes associated in pairs in synapsis
Synonyms, antonyms and the broader and narrower relations for bivalent come from Princeton University’s WordNet. Full sources and licences.