Green’s Dictionary of Slang

a drunkard.

[1826		Belfast Commercial Chron. 15 May 4/4: Sir Rumpot ran through his fortune and retired to India].
1914		Wash. Herald (DC) 19 Feb. 10/5: He knocked over a few old Barbary Coast ‘rum-pots’.
1931		D. Runyon ‘Lillian’ in Guys and Dolls (1956) 236: Of course nobody on Broadway blames Wilbur so very much for being such a rumpot.
1938		D. Runyon ‘Lillian’ in Runyon on Broadway (1954) 279: All he sees [...] is this rumpot ham, Wilbur Willard.
1947		N. Algren Neon Wilderness (1986) 87: Write down I plugged the old rumpot.
1952		I, Mobster 83: The governor out of a southern state who was nine kinds of a rumpot landed in town on a drunk.
1965		L. Haylen Big Red 17: Old Paddy, the rumpot getting his revenge out of a bottle.
1982		S. King Different Seasons (1995) 336: A couple of other local rumpots.
1993		S. King Dolores Claiborne 6: He wa’ant a week in the ground before that rumpot Harry Doucette come over with a friggin IOU.