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.
"Assuming the Fed leaves rates unchanged as expected, traders will be on the lookout for a potentially stronger description of inflation risks and/or possible wording to signal conditional tightening," said Matt Weller at City Index.
From Barron's ● Jul. 29, 2026
Those riffs will be on display at the Wacken Open Air festival on Friday and during McCreary’s eight-date September “Singularity” tour of the West Coast that hits L.A. on Sept. 17.
From Los Angeles Times ● Jul. 28, 2026
In modern Europe, August is the month when everyone seems to be on holiday.
From The Wall Street Journal ● Jul. 28, 2026
The iPhone and Apple Watch will be offered on 12- and 24-month terms while iPad and Mac will be on 24- and 36-month terms.
From MarketWatch ● Jul. 28, 2026
Instead, Greeley shrewdly noted Leah, “seemed to be on the most familiar terms with the knocking.”
From "American Spirits" by Barb Rosenstock
Definitions 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.
