noun
1.
a false or erroneous idea
his argument is based on a fallacy
Synonyms: erroneousness, error, fallaciousness, falsehood, falseness, falsity, untruth
Related Word: misconception, misconstrual, misinterpretation, misunderstanding
Contrasted words: comprehension, grasp, understanding; correctitude, correctness, truth
Antonyms: verity
2.
unsound and misleading reasoning
the fallacy of her theory is clearly evident
Synonyms: casuistry, deception, deceptiveness, delusion, equivocation, sophism, sophistry, speciousness, spuriousness
Related Word: elusion, evasion, inconsistency, quibble, quibbling