1 C1 idiomatic slang
To betray someone by informing on them to the police or another authority.
"He was grassed up by someone in his own crew."
separable
grass up
C1 slang separable transitive
To inform on someone to the police or another authority; a British slang synonym of 'grass on'.
In plain English
To tell the police or someone in charge that a person has done something wrong — seen as a big betrayal.
What does "grass up" mean?
One main meaning — here's how to use it.
Usage tip
British English slang. Interchangeable with 'grass on'. The separable form is notable: 'he grassed him up' rather than 'he grassed up him'. Very negative social connotation. Common in crime dramas and British vernacular.
Words that pair with "grass up"
Natural word combinations native speakers use most often.
police mate dealer suspect gang teacher
How to conjugate "grass up"
The five tense forms you'll use most often.
Base
grass up
I/you/we/they
3rd person
grasses up
he/she/it
Past simple
grassed up
yesterday
Past participle
grassed up
have + pp
-ing form
grassing up
continuous
Hear "grass up" in the wild
Listen to native speakers using "grass up" in real YouTube videos — click a clip to watch it on Looplines.
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