Green’s Dictionary of Slang

1. a hunchback; also used as a derog. name.

1744		A. Hamilton Gentleman’s Progress 109: Hump-back’d, and the tallest humpy I ever saw [HDAS].
1855		Bell’s Life in Sydney 17 Feb. 3/1: Humpy.—A man [...] whose back reminds us of the curious malformation attributed to the renowned Richard III.
1898		E. Pugh Tony Drum 45: I shall call you ‘Humpy,’ then.
1906		A. McCormick Tinkler-Gypsies of Galloway 298: Ye are a guid lad, humpy.
1949		W.R. Burnett Asphalt Jungle in Four Novels (1984) 219: ‘Come on, humpy,’ said the dick.

2. (Aus.) a camel.

1934		A. Russell Tramp-Royal 29: He is the despised ‘humpie’, the ‘filthy camel’.
1936		I.L. Idriess Cattle King 172: This country will owe the old ‘Humpy’ a debt of gratitude.
1945		Baker Aus. Lang. 214: A camel is an oont or a humpy.
1950		(con. 1936–46) K.S. Prichard Winged Seeds (1984) 126: His humpy and his mate’s are the only ones left on the track.

3. (N.Z.) a hump-backed whale.

2003

McGill Reed Dict. of N.Z. Sl.