IRRATIONAL Synonyms: 89 Similar and Opposite Words

irrational

adjective

i-ˈra-sh(ə-)nəl

Definition of irrational

as in unreasonable

not using or following good reasoning it's irrational to think that you can continue to consume an excess of calories and not gain weight

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Example Sentences

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Recent Examples of irrational Naturally, the mobile app includes a heaping helping of generative AI that aims to make sense of irrational financial markets. — Ryan Whitwam, ArsTechnica, 25 June 2026 If people believe regulatory caution invalidates every legal claim, courts may look irrational. — Alex Smolak, STAT, 27 June 2026 Economist Hyman Minsky spent his career explaining how irrational behavior produces fragility and instability in capitalist systems. — Hersh Shefrin, Forbes.com, 23 June 2026 Lagrange Numbers as a Measure of Irrationality At the end of the 19th century mathematician Andrey Markov took another pass at this challenge by omitting the golden ratio and focusing on the remaining irrational values. — Manon Bischoff, Scientific American, 19 June 2026 See All Example Sentences for irrational

Recent Examples of Synonyms for irrational

Adjective

If these requirements are not met, the search is unreasonable and therefore unlawful, and evidence obtained in that search cannot be used in court, barring a good-faith exception.

— Anne Toomey McKenna, The Conversation, 30 June 2026
Justices ruled that sweeping use of cellphone data requires a warrant, a decision applying the Fourth Amendment, which protects against unreasonable searches and seizures, to new technology.

— Josh Feldman, NBC news, 30 June 2026

Definition of unreasonable

Adjective

That difference suggests that the government sees this extension of patent rights as an illegitimate way for a company to exclude other companies from competing.

— Julie Dawson, The Conversation, 23 June 2026
Some fraudsters run an illegitimate DME company and get a doctor to prescribe the equipment.

— Janice Neumann, Chicago Tribune, 16 June 2026