be on
Idioms-
Be taking medication or an illegal drug, as in Are you on some antibiotic? or He was definitely on narcotics when it happened . [1930s]
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Be in favor of something or willing to participate, as in We're going dancing after the play—are you on? [ Colloquial ; late 1800s]
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Be engaged in some action, especially on the stage, as in Hurry up, you're on in five minutes . [Late 1700s]
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Perform extremely well, as in I can't return Dan's serve—he's really on today . [ Slang ; second half of 1900s]
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Be scheduled, as in Is tonight's rally still on? [ Colloquial ; second half of 1990s]
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be on one . Be at one's expense, either as a treat or the butt of a joke. For example, This round of drinks is on me , or He enjoys a good laugh, even when the joke's on him . [ Colloquial ; second half of 1800s]
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not be on . Be unacceptable, not allowable, as in I can't believe you'd cancel; that's just not on . This usage is more common in Britain than America. [ Colloquial ; 1930s] For a synonym, see not done . Also see be on to .
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see be on.
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.
"We are waiting to see what the outcome will be on that day, the judgement for everything we have been experiencing for generations," said a 25-year-old Yangon-based Rohingya activist who requested anonymity for security reasons.
From Barron's ● Nov. 14, 2026
“I wanted to be on TV,” says White, co-host of the syndicated game show, “Wheel of Fortune.”
From Los Angeles Times ● Nov. 13, 2026
Will Atiku Abubakar be on Nigeria's presidential ballot after court ruling?
From BBC ● Nov. 12, 2026
After a yearslong crisis, exacerbated by last year’s record-breaking Los Angeles County infernos, California’s home-insurance sector appears to be on the brink of recovery.
From The Wall Street Journal ● Nov. 12, 2026
Orville Payne told me to be on the lookout for you.
From "The Seven Wonders of Sassafras Springs" by Betty G. Birney
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Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
