Green’s Dictionary of Slang

a hermaphrodite.

1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 210: [...] whether derived from the muff worn by ladies, for the most part, or hermaphrodite abbreviated, is uncertain; but he who fails in an endeavour, is said to ‘make a moph of it,’ and if he is commonly guilty of failure, he is himself ‘a proper moph.’.
1966		Trimble 5000 Adult Sex Words and Phrases.