A fast horse. Obsolete.

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1848.  

        I took her out to Harlem,—
  On the road we cut a swell,
And the nag we had before us
  Went twelve miles before he fell;
And though, ven he struck the pavement,
  The “crab” began to fail,
I got another mile out
  By twisting of his tail.
Durivage and Burnham, ‘Stray Subjects,’ p. 108 (Phila.).    

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1852.  He does not keep a ‘fast crab’ now himself; he is too intent on making a fortune.—C. A. Bristed, ‘The Upper Ten Thousand,’ p. 20 (N.Y.).

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1857.  A calm, frosty, moon-shiny night; a clipper of a sleigh under you; a pair of ‘fast crabs’ before you; and a pair of sparkling eyes, illuminating a pair of rosy cheeks, by the side of you; and the sleigh-bells making such a noise that you and the owner of the eyes and cheeks have to put your heads together in order to make yourselves heard.—Knick. Mag., l. 435–6 (Nov.).

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