supergrass
/ˈsuːpɚˌgræs/
Brit
/ˈsuːpəˌgrɑːs/
noun
plural
supergrasses
/ˈsuːpɚˌgræs/
Brit
/ˈsuːpəˌgrɑːs/
noun
plural
supergrasses
Learner's definition of SUPERGRASS
[count]
British, informal
:
a criminal who gives information to the police about a large number of other criminals