Having slender hams shaped like a sickle.

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1840.  You see [him] mounted on his crop-eared, bushy-tailed mare, the obliquity of whose hinder limbs is described by that most expressive phrase, “sickle hams.”… Our militia general, with his crop-eared mare, with bushy tail and sickle hams, would frighten a hundred Alexanders.—Mr. Thomas Corwin of Ohio, House of Representatives, Feb. 15: Cong. Globe, p. 785, App.

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1848.  The horse was snip-nosed, big-headed, ewe-necked, swag-backed, hog-rumped, sickle-hammed, timber-limbed, knock-kneed, and clump-footed.—Mr. Wick of Indiana, the same, April 25: id., p. 668.

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