Green’s Dictionary of Slang

1. (US) arrogant.

1979

‘Iceberg Slim’ Airtight Willie and Me 48: Mama and Miss Anne kept their asses pretty and prissy like muckety muck white bitches.

2. powerful, influential.

1997

T. Fontana ‘A Game of Checkers’ Oz ser. 1 ep. 8 [TV script] That’s Kareem Said. He’s the big muckety-muck Muslim.