Green’s Dictionary of Slang

(US) an umpire.

1908		N.Y. Eve. Journal 4 May in Fleming Unforgettable Season (1981) 60: I don’t blame [players] for getting hot, sore and mad [with] slow thinking, slow moving umps.
1914		‘High Jinks, Jr’ Choice Sl. 74: Every time that Umps starts talking his tongue gets twisted around his eye tooth and he can’t see what he’s saying.
1915		Seattle Star (WA) 3 June 7/3: [headline] Umpi Slips One Over the Boys.
1919		Van Loan ‘Excess Baggage’ in Score by Innings (2004) 403: When he finally gets it through his head that he is the party the ump is after, he chucks away his glove.
1920		A. Baer Says ‘Bugs’ Baer 14 Aug. [synd. col.] International League umps have no rough edge on the bigger league weather forecasters .
1944		T. Thursday ‘Base on Balds’ in Sports Winners Spring 🌐 ‘Stir-rike!’ bellows the ump.
1952		B. Malamud Natural 46: I’d’ve thrown him out too if I was the ump.
1978		R. De Christoforo Grease 109: ‘Strike!’ the ump yelled.
1983		N. Proffitt Gardens of Stone (1985) 178: Can you get me a Nam veteran for an ump?
2000		P. Temple Dead Point (2008) [ebook] Things wouldn’t be so bad [...] if that bloody ump hadn’t found a free for the bastards.