cayuse, n. — Green’s Dictionary of Slang

cayuse n.

[‘The wild horse of Oregon, named for the Cayuse Indians, an equestrian people... . The name is now commonly used by the northern cowboy to refer to any horse. At first the term was used for the western horse, to set it apart from a horse brought overland from the East. In later years the name came to be applied as a term of contempt to any scrubby, undersized horse.’ Francis Haines, Western Horseman, II no. 2 (March–April 1937)]

(US)

1. (also cayouse) an Indian pony.

1857		Oregon Weekly Times Jan. n.p.: Davis and Monnastes advertise that they can do ‘all manner of wrought and cast work, from a Stream Engine and Boiler down to shoeing a “Cultus” Cayuse Horse.’.
1867		Territorial Enterprise 31 Jan. 2/4: Jane [...] was mounted behind her lover and away, nor bated they the noble cayuse till many a league was passed [DA].
1897		A.H. Lewis Wolfville 192: If you can’t get along with that cayouse [...] it’s foreordained you-all has to go afoot.
1905		H. Green Actors’ Boarding House (1906) 96: Hey, Fat Belly, ketch them cayuses before they stampede!
1914		East Oregonian 24 Sept. 13/1: You ride that yere cayuse to Athena.
1922		N.Y. Tribune 5 Nov. 3/4: The little family party probably has motored to town as the Indian cayuse is in the discard .
1931		O. Strange Law O’ The Lariat 153: Yu fork a cayuse an’ mosey along.
1938		B. Conlon ‘Rope Meat’ in Wild West Weekly 22 Oct. 🌐 Leastwise, leave me my cayuse.
1948		Chicago Trib. 27 May II 2/6: Life atop a cayuse in the professional arenas [...] is no easier than one astride a bronco on the college rodeo field [DA].

2. any (inferior) horse; occas. attrib. (see cit. 1881).

1881		‘Bill Nye’ Bill Nye and Boomerang 17: He jabs the Mexican spurs into the foamy flank of his noble cayuse plug.
1889		Kipling ‘A Little More Beef’ in Civil & Military Gaz. 18 Sept. (1909) 52: [W]oe betide the luckless cayuse that stumbled in that ride.
1902		Sumpter Miner (OR) 31 Oct. 10/2: The cayuse doesn’t weigh that much [...] he is sold to a butcher and cut up into meat to feed soldiers.
1907		C.E. Mulford Bar-20 ii: I heard tell that they make glue outen cayuses, sometimes.
1911		J. Lomax Cowboy Songs 198: And the cowboy riz up sadly / And mounted his cayuse.
1922		P.A. Rollins Cowboy 192: Look here, you dodgasted, pale pink, wall-eyed, glandered, spavined cayuse.
c.1935		N. Algren ‘A Holiday in Texas’ in Texas Stories (1995) 40: Git on out now [...] go ride yo’re own cayuse.
1947		W.D. Overholser Buckaroo’s Code (1948) 83: Go get that cayuse.
1951		in Randolph & Legman Ozark Folksongs and Folklore (1992) II 652: They were hot-headed cayuses, just like their dad.
1969		Glenn Orhlin ‘Bawdy Strawberry Roan’ 🎵 I found myself hired / T’ snap out some bronc’s / This roan stud had sired / Their knot-head cayuse’s / Just like their Dad.
1972		(con. 1916) G. Swarthout Tin Lizzie Troop (1978) 206: Dinkle [...] slapped on a saddle, and three men maneuvered the pilot onto the cayuse.

3. a worthless person.

1905		Nat. Police Gaz. (NY) 9 Dec. 7: You show signs of bein’ a some inquisitive cayuse .
1929		‘Max Brand’ ‘The Ghost’ in Goodstone Pulps (1970) 63/1: Tell me what the wall-eyed cayuses figure on doin’!