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.
"I really worried about having to be on my own," says Izzy Garcez, 20, who thought she would miss spending evenings with her family and having people to eat and watch TV with.
From BBC ● Aug. 15, 2026
So if a new buyer buys a home at a significantly higher price, then they could be on track to pay a much higher tax bill.
From MarketWatch ● Aug. 15, 2026
For those who love dogs, offensive tackle Vincent Shields of Murrieta Valley High needs to be on your must-invite list.
From Los Angeles Times ● Aug. 15, 2026
The former song is a prog-rock instrumental, while the latter is a yearning piece about striving for success: “I’ve got to keep on chasin’ a dream / I’ve gotta be on my way.”
From The Wall Street Journal ● Aug. 15, 2026
Why should pizzas be on the way when she already had a refrigerator bursting with food and the boy had gone to school so many days with his stomach rumbling, his head aching?
From "Not Nothing" by Gayle Forman
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.
