Synonyms

no-no

American

[noh-noh] / ˈnoʊˌnoʊ /

noun

Informal.

plural

no-nos, no-no's

anything that is forbidden or not advisable, as because of being improper or unsafe.

If you want to lose weight, rich desserts are a no-no.

Etymology

Origin of no-no

1940–45, reduplication of no ¹

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.

Putting EU money behind nuclear projects was long a no-no, with the 27-nation bloc focusing on renewables in the race to cut planet warming emissions.

From Barron's • Mar. 10, 2026

“Natural light is the best. I can’t do a dark house. The no-no of no-nos is bad floor plan and flow, and not enough natural light.”

From MarketWatch • Nov. 24, 2025

Telling shoppers their goods are only worth a fraction of what they originally paid for them is also a no-no for brands.

From The Wall Street Journal • Oct. 19, 2025

In the sixth inning, Miguel Rojas finally broke up the no-no, adjusting to yet another cutter for a line-drive single to right.

From Los Angeles Times • Aug. 23, 2025

Somebody two people down from us is eating Chinese food, and even I know that’s a no-no in a small space.

From "Better Nate Than Ever" by Tim Federle

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023