Definition of "no-no" []

• Informal Something unacceptable or impermissible: "Even though his company wasn't the one involved in the case, what he did is considered a definite no-no” ( Mike Royko). (noun)
• Informal A social blunder; a faux pas. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Even information about the swimsuit is a no-no in Saudi Arabia, where a vigilant government blocks Western websites displaying or advertising the sale of bikinis."
• "Had he been able to finish off another no-no, Verlander would have become just the sixth player in baseball history to throw three or more no-hitters, and yet he still would have only been 43% of the way to matching Ryan's mark."
• "If we just had a private plane for our personal pleasure, that would be a big no-no."