illogical
Americanadjective
adjective
-
characterized by lack of logic; senseless or unreasonable
-
disregarding logical principles
Other Word Forms
Etymology
Origin of illogical
Explanation
When there's no good reason or explanation for something, don't fret; chances are it's illogical — meaning that it has no rational explanation behind it. The word logic has origins in the Greek root logos meaning "reason, idea, or word." But slap the prefix il- in front of it, and suddenly the word reverses its meaning. Illogical? Check out other words with the same prefix, like illegitimate and illegal, and you'll quickly see that the prefixil- in front of a word starting in "l" means "not." Suddenly the meaning of illogical isn't quite so illogical after all, is it?
Vocabulary lists containing illogical
Inside Out & Back Again
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
The Devil's Arithmetic
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Way Off: Synonyms for "Wrong"
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The results may help explain behavior that can otherwise seem illogical in daily life.
From Science Daily ● Aug. 13, 2026
Sources close to the player felt it was illogical to think a club would come in and offer more than Barcelona would have had to pay.
From BBC ● Jul. 20, 2026
Although this sequence seems illogical, it is arguably allowed under current accounting rules.
From MarketWatch ● Apr. 27, 2026
The idea that a warning should change the legal calculus of excessive force, now at the center of both of these cases, is callous and illogical.
From Slate ● Apr. 21, 2026
Amity would not allow a schism; no one in Abnegation would be so selfish; Candor would argue until they found a common solution; and even Erudite would never do something so illogical.
From "Insurgent" by Veronica Roth
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
