Did you know?

Click any word in a definition or example to find the entry for that word

grass up - definition and synonyms


What are red words?

90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.



The thesaurus of synonyms and related words is fully integrated into the dictionary. Click on the thesaurus category heading under the button in an entry to see the synonyms and related words for that meaning.

phrasal verb [transitive] British informal
Word Forms
present tense
I/you/we/theygrass up
he/she/itgrasses up
present participlegrassing up
past tensegrassed up
past participlegrassed up
  1. to tell someone in authority, especially the police, about something bad that someone else has done

    You wouldn’t grass up an old mate, would you?

    Who grassed him up to the police?

See also main entry: grass


to fall over forwards so that your face hits the ground or another surface

BuzzWord Article

Open Dictionary


the activity of exploring abandoned buildings and other manmade structures

add a word


A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today.

global English and language change from our blog
Macmillan learn live love play