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

During his more-than-four-hour closing argument, the attorney dismissed claims that Combs Global (née Combs Enterprises) is a racketeering enterprise, saying the idea is preposterous. —Kevin Dolak, HollywoodReporter, 27 June 2025

The plot is preposterous; Pitt is an old driver who hasn’t raced F1 in 30 years, but he is lured across the pond midseason by a long time friend, team owner Javier Bardem. —Mac Engel, Fort Worth Star-Telegram, 25 June 2025

Undeterred, Lindell has continued to push preposterous and thoroughly debunked claims about the election. —Krista Kafer, Denver Post, 20 June 2025

Despite the claims of the preposterous Baghdad Bobs on TV (at least one of whom is pocketing a hack state pension of $156,281 a year), the persecution produced no real evidence. —Howie Carr, Boston Herald, 12 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.