chump

 
Pronunciation: /tʃʌmp/

noun

  • 1 informal a foolish or easily deceived person: I was left feeling a bit of a chump
  • 2British the thick end of something, especially a loin of lamb or mutton.

Phrases

off one's chump

British informal mad: I was beginning to think he’d gone off his chump

Origin:

early 18th century (in the sense 'thick lump of wood'): probably a blend of chunk1 and lump1 or stump