be on

Idioms  

1. Be taking medication or an illegal drug, as in Are you on some antibiotic? or He was definitely on narcotics when it happened . [1930s]

2. Be in favor of something or willing to participate, as in We're going dancing after the play—are you on? [ Colloquial ; late 1800s]

3. Be engaged in some action, especially on the stage, as in Hurry up, you're on in five minutes . [Late 1700s]

4. Perform extremely well, as in I can't return Dan's serve—he's really on today . [ Slang ; second half of 1900s]

5. Be scheduled, as in Is tonight's rally still on? [ Colloquial ; second half of 1990s]

6. 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]

7. 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 .

8. see be on.

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Example Sentences

"There was a point I just did not want to be on this planet because it was just horrific," the activist and author told BBC News NI.

From BBC • May 17, 2026

Nomura analysts warn more drastic measures may be on the anvil.

From Barron's • May 17, 2026

But I wouldn’t put it past him to be on some Chaotic Good-type skulduggery spreading the rumor that he is bigger than streaming’s infrastructure.

From Los Angeles Times • May 15, 2026

“The point is, a lot more eyeballs will be on the industry. Which is a good thing,” Taylor told MarketWatch this week.

From MarketWatch • May 15, 2026

I’d have done what I needed to, and I’d be on my way back to the classroom.

From "Ida B" by Katherine Hannigan

Related Words

• display
• execute
• give
• go on
• offer
• play
• present
• produce
• represent
• show
• stage