1. the quality of being superficially plausible but actually wrong or misleading

Examples

• The speciousness of his argument became clear when we examined the evidence.
• Despite the speciousness of the proposal, many voters were initially convinced.
• The lawyer exposed the speciousness of the witness’s testimony.
• Her presentation had an air of speciousness that made me suspicious.
• The speciousness of the advertisement’s claims led to consumer complaints.
• Critics pointed out the speciousness of the politician’s promises.