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
• foolish
• unreal
• insane
• fantastical

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

To the contrary, his hunger for attention was, then as now, embodied by his preposterous signature. —David Remnick, New Yorker, 3 Aug. 2025

There was no reason for the feds to pour good money after bad supporting a preposterous project that doesn’t have any national significance. —Rich Lowry, National Review, 19 July 2025

Alternative ways to score lounge benefits Only 10 years ago, the idea of paying $450 a year for a credit card seemed preposterous for most Americans. —Katherine Fan, AFAR Media, 16 July 2025

The question itself was preposterous before the recent streak. —Greg Cote july 20, Miami Herald, 20 July 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.