falsehood has 3 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 one recorded opposite is truth.
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 falsehood come from Princeton University’s WordNet. Full sources and licences.
the act of rendering something false as by fraudulent changes (of documents or measures etc.) or counterfeiting