An important, powerful or influential person; muckamuck.
1755, Samuel Foote, The Grand Panjandrum (a nonsense poem written to test actor Charles Macklin's claim that he could accurately recite any paragraph of text after a single reading),
So he died, / and she very imprudently married the Barber: / and there were present / the Picninnies, / and the Joblillies, / and the Garyulies, / and the great Panjandrum himself, / with the little round button at top;
1910, Eliakim Littell, Making of America Project, Robert S. Littell, Living age ... (Littell's Living Age), Volume 265, page 809,
I think it's an excellent thing that the Great Panjandrum is coming for the week-end. Have you ever met him in private?"
I ought to explain that the Great Panjandrum was the nickname for Lord Elkindale, the then Foreign Secretary.
A self-important or pretentious person.
(military) A massive, rocket-propelled, explosive-laden cart designed by the British military during World War II.