be on one
C1 slang inseparable intransitive
In simple words
To be acting very wild, excited, or like you've had too much to drink or taken something.
Meanings
1 C1
idiomatic
slang
(British slang) To be in a state of extreme excitement or high energy, often due to alcohol, drugs, or sheer enthusiasm.
"She was absolutely on one last night — dancing until four in the morning."
Grammar: inseparable
Usage notes
Very British, very informal. Commonly heard in club or party settings. Can refer to alcohol or drug intoxication, or simply to someone being in a very excitable mood. Not appropriate in formal contexts.
Commonly used with
night out party dancing completely absolutely totally
Forms
Base
be on one
I/you/we/they
3rd person
is on one
he/she/it
Past simple
was/were on one
yesterday
Past participle
been on one
have + pp
-ing form
being on one
continuous
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