Definition of high muck-a-muck in English:

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.

    ‘he was once a high muckety-muck at the CIA’
    • ‘I'm lunching with Josh Jones, one of the high muck-a-mucks of Dreamhost, the company that hosts this website on its massive servers.’
    • ‘He also was the son of a high muck-a-muck in the Nixon administration so he could have had info to pass on before he got his job in the White House.’
    celebrity, famous person, very important person, personality, name, big name, famous name, household name, star, superstar, celebutante, leading light, mogul, giant, great, master, king, guru
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Origin

Mid 19th century: perhaps from Chinook hiyu plenty + muckamuck food from Nootka ḥayo ten + maṙhoṙmaq- choice wheatmeal with high substituted for hiyu.

Pronunciation:

high muck-a-muck

/ˌhī ˈməkəˌmək/