Green’s Dictionary of Slang

(orig. US) an important (or self-important) person; also adj.

1855		Broadway Belle (NY) 1 Jan. n.p.: The Grand High Cockalorum of the Five Point House of Industry.
1878		Western Times 25 Oct. 5/4: The grand policy of ‘Imperialism,’ which is his master’s conjuring ‘high cockalorum’ phase.
1880		Era 11 Jan. 12/1: In this scene, too, we make the acquaintance of his Majesty King Cockalorum Cash.
1882		Bristol Magpie 21 Sept. 3/2: ‘Now you look here, young cockalorum’.
1886		Lantern (N.O.) 27 Oct. 3: They would imagine he was some pumpkins amongst the political high-cock-a-lorum’s of Carrollton.
1886		Royal Cornwall Gaz. 29 Oct. 4/2: He did not wish to be ‘Lord High Cockalorum of the city’.
1893		D. Barber et al. (eds) 93 S Class Book Yale U. (New Haven, CT ) 26: herbert leroy potter [...] his great-great-grandfather was a high cockalorum in the Revolutionary War.
1896		Regiment 11 July 231/3: I shall have to beg some biscuits and sugar from the High Cockalorum of England.
1900		Bulletin (Sydney) 22 Dec. 28/1: Being pressed for payment, he assumed his casual character of high cockalorum to a certain lodge, and declared himself on the lodge whereof his physician was the contracting cure-all.
c.1900		F. Leo [perf. Wilkie Bard] ‘All Becos ’e’s Minding a ’ouse’ 🎵 ‘I say, cockalorum, 'ow much longer 'ave yer got / Before the boss come 'ome and chucks yer out?’.
1901		J. London ‘Local Color’ Complete Short Stories (1993) I 688: I pray the the way to the sanctum sanctorum, to the Most High Cockalorum.
1910		in Western Weekly News (Devon, UK) 12 Mar. n.p.: Carr’d aroun’ a petition, he did, to zend in to the high-cockalorum o’ the police.
1914		Sport (Adelaide) 14 Mar. 5/5: How is Pearl, Jack, old cockalorum .
1925		C.H. Claudy Old Tiler Talks 5: People who want to play politics and be called the Grand High Cockalorum of the Exalted Central Chamber of the Secret Sanctorum.
1937		E. Raymond Marsh 361: The Secretary of State, having given careful consideration to the petition of Young High-cockolorum, sees no ground for granting his request.
1940		M. de la Roche Whiteoak Heritage (1949) 55: He’ll soon find out he can’t be high cockolorum here.
1952		(con. late 19C) Stanley Vestal Dodge City: Queen of Cowtowns 58: He said each comprised three outside men, one high cockalorum behind the case, and one inside capper!
1976		Jack Kramer Travels with the Celestial Dog 22: My high-cockalorum social and political deliberations.
1990		C. Palmer Wild Winds 135: Thinks he’s some kind of high cockalorum, he does.