1 C1 idiomatic slang
To inform on someone to an authority figure, especially the police, in a way seen as a betrayal.
"Nobody likes him at school because he's always grassing on his classmates."
inseparable
grass on
C1 slang inseparable transitive
To inform on someone to an authority, especially the police, in a way considered disloyal or treacherous.
In plain English
To secretly tell the police or someone in charge about what another person has done wrong.
What does "grass on" mean?
One main meaning — here's how to use it.
Usage tip
Primarily British English slang. Considered a serious social betrayal in many communities. 'Grass' as a noun (meaning 'informer') derives from Cockney rhyming slang: 'grasshopper' = 'copper' (police), or possibly from 'snake in the grass'. Very negative connotation.
Words that pair with "grass on"
Natural word combinations native speakers use most often.
police teacher boss someone authorities neighbour
How to conjugate "grass on"
The five tense forms you'll use most often.
Base
grass on
I/you/we/they
3rd person
grasses on
he/she/it
Past simple
grassed on
yesterday
Past participle
grassed on
have + pp
-ing form
grassing on
continuous
Hear "grass on" in the wild
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