preposterous

adjective

pre·​pos·​ter·​ous pri-ˈpä-st(ə-)rəs 

: contrary to nature, reason, or common sense : absurd

preposterously adverb

preposterousness noun

Synonyms

• absurd
• bizarre
• crazy
• fanciful
• fantastic
• fantastical
• foolish
• insane
• nonsensical
• unreal
• wild

Examples of preposterous in a Sentence

The whole idea is preposterous!

the idea that extraterrestrials built the pyramids is preposterous

Recent Examples on the Web

This was a preposterous undertaking, like trying to rank the various pixels of a magic eye poster. —Pitchfork, 6 June 2025

Not only that, but 2024 was a preposterous statistical season for the Broncos’ 2021 first-round pick. —Parker Gabriel, Denver Post, 5 June 2025

Now the splendidly preposterous charm is the face of actor Kevin Spacey embossed on a lucky sweatshirt. —Jeff Kleinman, Miami Herald, 3 June 2025

Yet, although nobody knows the true number — partly because the cancellation of programs means that no one is counting the dead — the flat denial of any deaths at all is preposterous. —Nicholas Kristof, Mercury News, 3 June 2025

Word History

Etymology

Latin praeposterus, literally, in the wrong order, from prae- + posterus hinder, following — more at posterior

First Known Use

1533, in the meaning defined above

Kids Definition

preposterous

adjective

pre·​pos·​ter·​ous pri-ˈpäs-t(ə-)rəs 

: making little or no sense : absurd

preposterously adverb

preposterousness noun

Etymology

from Latin praeposterus, literally, "having the rear part in front," from prae- "in front, before" and posterus "coming behind, following"

Word Origin

The familiar expression "putting the cart before the horse" comes very close to the literal sense of the word preposterous. The Romans formed their Latin adjective praeposterus from prae-, meaning "before," and posterus, meaning "following." They at first used it to mean "having that first which ought to be last," like having a cart ahead of the horse that is pulling it. Praeposterus was used to describe something that was out of the normal or logical order or position. From this developed the more general sense of "ridiculous, absurd." These meanings were borrowed into English in the 16th century. Although preposterous is seldom used in its literal sense nowadays, we still use it to describe something that seems so unreasonable as to be ridiculous.