high muck-a-muck

 
(also high muckety-muck)

noun

North American informal
  • a person in a position of authority, especially one who is overbearing or conceited: a high muck-a-muck at the CIA

Origin:

mid 19th century: perhaps from Chinook hiyu 'plenty' + muckamuck 'food', from Nootka ḥayo 'ten' + ma˙ho˙maq- 'choice wheatmeal', with high substituted for hiyu