grass up

verb

To betray by informing on.

Similar
drop a dimename namessnitch
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Meanings

verbgrass up (third-person singular simple present grasses up, present participle grassing up, simple past and past participle grassed up)

present singular third person grasses up · participle present grassing up · participle past grassed up · past grassed up

  1. UKslangTo betray by informing on.

    My sister grassed me up to the caretaker! She thought she was doing me a favour — by grassing me up she was sure he'd let me off.

    1999, Angela Devlin, Bob Turney, Going Straight: After Crime and Punishment, →ISBN

    Synonyms: drop a dime, name names, snitch

Synonyms & antonyms

verbTo betray by informing on.

Similar
drop a dimename namessnitch
Also see
bewrayblowdimedime outdrop a dimedrop a dime on someonefinkfizgiggrassinform onname namesnarkpeachrat outroll onshopsnitchsqueaksquealtelltip off

Origin

From grass (“informer”) + up.

Full word history & related roots →
Cite this entry
APA

grass up. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/grass%20up

MLA

“grass up.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/grass%20up. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “grass up,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/grass%20up.

Source: grass up on Wiktionary, CC BY-SA 4.0.