Definition of jack-pudding:
(n) :
A coarse medieval coat of defence, especially one made of leather.
(n) :
A man.
(n) :
(chiefly capitalized) A name applied to a hypothetical or typical man.
(n) :
(countable, now chiefly US) A man, a fellow; a typical man; men in general.
(n) :
(colloquial) A sailor.
(n) :
(slang) A policeman or detective; (Australia) a military policeman.