1. completely unreasonable, illogical, or inappropriate; absurd

Examples

• It’s preposterous to think we can finish this project in one day.
• The idea that cats can fly is absolutely preposterous.
• She made a preposterous claim about meeting aliens.
• The price they’re asking for that old car is preposterous.
• His preposterous behavior at the meeting shocked everyone.
• The notion that homework should be banned is preposterous.