grass - definition and synonyms

verb [intransitive] British informal 

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/ɡrɑːs/
present tense
I/you/we/theygrass
he/she/itgrasses
present participlegrassing
past tensegrassed
past participlegrassed
  1. to tell someone in authority, especially the police, about something bad that someone else has done
    grass on:

    He was too loyal to grass on his own brother.

phrasal verbs