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

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

From MarketWatch • Feb. 17, 2026

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

“Using AI to help prepare for interview questions is fine, but reading off a screen with interview responses is a total breach of trust and a big no-no for me,” she said.

From Los Angeles Times • Apr. 11, 2025

She learned that golden retrievers are not ponies, peas taste funny, dead flies on the floor are a no-no, but candy is really good.

From "Out of My Mind" by Sharon M. Draper

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