Green’s Dictionary of Slang

1. anything exceptional or particularly admirable of its type.

1751		Smollett Peregrine Pickle (1964) 597: ’Sblood! a believe master thinks I have no more stuff in my body than a dried haddock, to turn me adrift in the dark with such a spanker.
1792		C. Dibdin ‘Bonny Kitty’ Buck’s Delight 53: Our voyage was a spanker, / And bran new was every sail.
1800		‘The Sailors Consolation’ Jovial Songster 45: He overboard tipt, when a shark, and a spanker, / Soon nipt him in two.
1843–44		Dickens Martin Chuzzlewit (1995) 259: A first-rate spanker, cap’en, was it? Yes?
1858		Huddersfield Chron. 29 May 3/1: ‘Be the power o’ yer grate gran’mother’s pot-stick [...] an’ a spanker it was’.
1865		Dickens Our Mutual Friend (1994) 181: ‘Yes,’ said Mr. Boffin, ‘it’s [i.e. a new house] to be a Spanker.’.
1880		Bulletin (Sydney) 11 Dec. 12/1: Isn’t your mother a lovely creature, a regular spanker?
1888–94		‘Walter’ My Secret Life (1966) II 276: A tall, fine, stout, healthy, country woman, a regular spanker.
1892		‘’Arry in Venice’ in Punch 27 May 88/1: Friend Imre’s a spanker, you bet, and quite fly to the popular fake.
1920		R. Lardner Big Town 237: If Thornton had been nosing round for six months and didn’t know till now that they was a spanker like Bobbie in the family circle, I wouldn’t hardly call Maizie the town gossip.
1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 181: Thirty years earlier he or she would have been a ‘stunner’; a hundred years earlier a ‘spanker’.

2. a fast horse or ship, any creature.

1814		W. Scott Waverley (1821) 288: And ye wanted a spanker that would lead the field, [...] I would serve ye easy.
1831		Quizzical Gaz. 27 Aug. 2/1: To be Sold.— A strong, staunch, steady, asound, stout, safe, sinewy servicable, strapping [...] sorrel steed of superlative symmetry styled Spanker.
1836		T. Haliburton Clockmaker I 155: We shall progress real handsome now; that are horse goes etarnal fast [...] He’s a spanker, you may depend.
1859		Hotten Dict. of Modern Sl. etc.
1868		Liverpool Mercury 2 Dec. 3/1: A thief in cant language would term a horse a ‘prancer’ or a ‘prad’ while in slang a man of fashion would speak of it as a ‘bit of blood’ or a ‘spanker’.
1870		Hotten Sl. Dict.
1873		N.S. Dodge ‘Vagrants and Vagrancy’ in Appleton’s Journal (N.Y.) 6 Sept. 308: To a vagrant, a horse is a prad; to a man of fashion, a spanker. The former is cant, the latter slang.
1903		Bulletin (Sydney) 2 July 34/1: This ’ere belonged to Paul Verlaine, / A spanker in his time; / An’ this was Robert Browning’s steed, / Near strangled with a rhyme.