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.
Rome, from Mount Aventine features a panoramic view of the Italian capital and will be on display at the Palazzo Rondinini for three days.
From BBC ● Sep. 29, 2026
And baseball’s best rivalry will be on October display only if the Dodgers and San Diego Padres meet in the NL Championship Series.
From Los Angeles Times ● Sep. 28, 2026
I’d rather be on a beach in Bali than watching my spouse sit at the computer.
From MarketWatch ● Sep. 28, 2026
“We are the people on the ground, so most of the impact will be on us,” said Wilson Kuria, a guide who started a petition opposing Uber Safari.
From The Wall Street Journal ● Sep. 27, 2026
“You’d better be on your way. Tell your mother, if she wants to ride in with us, to be ready first thing in the morning.”
From "Summer of the Monkeys" by Wilson Rawls
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.
