Green’s Dictionary of Slang

a small person, an insignificant person; thus as a nickname.

1701		N. Ward ‘Battel without Bloodshed’ in Writings (1704) 113: The Tall-man with Pike, and the Short-Arse with Gun.
1706		E. Phillips New World of Words (6th edn) n.p.: Spud, [...] a Short-arse, or little despicable Fellow.
1850		Fast Man 6:1 n.p.: Mr. [? Hurst] said he'd got his cocked hat and staff outside, and if they liked he’d soon have order. a voice.—‘Sit down. Short a—!’.
1943		R. Llewellyn None But the Lonely Heart 253: Come on, shortarse, where’s the doings.
1951		(con. 1941) E. Lambert Twenty Thousand Thieves 221: Hey, shortarse! [...] You with the pips. Show us yer face.
1963–74		B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 109: Thank cripes you were approximately in the vicinity, Shortarse.
1965		G. Melly Owning Up (1974) 205: A four-eyed short-arse, which makes its nest in old New Statesmans.
1985		‘Thommo’ Dict. Aus. Swearing & Sex Sayings 118: SHORT ARSE — A person of lower than average height.
1989		T. Blacker Fixx 83: ‘Step aside, Shortarse,’ I said to a tall, skinny youth.
1997		(con. 1950s) J. Byrne Slab Boys [film script] 62: I’m no’ tellin’ you again, shortarse.
1998		(con. c.1950) Malcolm S Mathews Myself and Others 🌐 He glanced speculatively at Shortarse, but mercifully refrained from comment.
1999		G. Seal Lingo 123: The short-arse is a person of small stature.
2000		M. Amis Experience 14: I always feel such a short-arse in the Picasso.
2012		(con. 1980s) I. Welsh Skagboys 332: Any hands-on involvement in a skrimish wi a short-arse nancy can only diminish their standing.
2016		A. Wheatle Crongton Knights 118: ‘And say he turns round and says, “Screw you, short-ass,” and cracks up laughing’.
2019		M. Herron Joe Country [ebook] [H]aving, as she put it, a lower centre of gravity: lot of syllables for shortarse.