Synonyms

no-no

American

[noh-noh] / ˈnoʊˌnoʊ /

noun

Informal.

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.

Other Word Forms

Noun Inflected Forms

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.

"In a very patriarchal society, to have a woman sitting at the helm was a major no-no," she told the court, suggesting this had made her a target for unnamed male opponents.

From BBC • Jun. 17, 2026

The Spurs kept knocking him and chasing him the length of the floor—Wembanyama even floated a foot underneath a Brunson 3-point attempt, a possible flagrant no-no the referees ignored—and it only made him stronger.

From The Wall Street Journal • Jun. 14, 2026

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

The biggest no-no: Uploading documents with personal information into a publicly available AI tool.

From MarketWatch • Feb. 17, 2026

He’s too polite to mention that they’re outside in their pajamas, usually a big no-no.

From "Merci Suárez Changes Gears" by Meg Medina

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