Definition of "shamoy"

[H]e seldom donned his armour, substituted costly damask and silk for his war-worn shamoy doublet, and affected at his advanced time of life more gaiety of attire than his contemporaries remembered as distinguishing his early youth.

1825 June 22, [Walter Scott], chapter XVI, in Tales of the Crusaders. […], volume I (The Betrothed), Edinburgh: […] [James Ballantyne and Co.] for Archibald Constable and Co.; London: Hurst, Robinson, and Co., page 317

I afterwards adopted the precaution of using very thin shamoy gloves, and have often taken observations at still lower temperatures without injury.

1843, Thomas Simpson. Narrative of the Discoveries on the North Coast of America, effected by the Officers of the Hudson’s Bay Company, during the years 1836—39 (London : S. & J. Bentley, Wilson, and Fley), p. 39