CAYUSE

[Alan H. Hartley]

Following is the entire OED2 entry:

CAYUSE. U.S. local. Also †kiyuse, †skyuse.
[Said to be from the language of the Chinook Indians of Oregon.]
‘A common Indian pony’ (Scribner’s Mag. II. 510). Also, any horse (N.
Amer. colloq.).
1841 T. J. Farnham Trav. Gt. West. Prairies 157 Skyuse horses never make
such disagreeable mistakes.
1857 Oregon Weekly Times Jan. (Th.), All manner of wrought and cast
work,..down to Shoeing a ‘Cultus’ Cayuse Horse.
1867 Territorial Enterprise (Virginia, Nev.) 31 Jan. 2/4 Jane..was
mounted behind her lover and away, nor bated they the noble cayuse till
many a league was passed.
1869 A. K. McClure Rocky Mts. 302 Twice our kiyuse broke nearly out of
the harness... The kiyuse is never perfectly tamed.
1873 J. H. Beadle Undevel. West xxxv. 750, I mounted a cayuse and rode
seven miles over the hills.
1882 Blackw. Mag. Dec. 768, I stopped to let the old cayuse rest.
1885 Century Mag. Nov. 33 As firm a seat..as any cowboy that ever put
leg over a cayuse.
1948 Chicago Tribune 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.
1962 Field, Horse & Rodeo (Calgary) Nov. 30/1 Well, chances are Mr.
Dude, you’ve been getting a silent horse laugh yourself from your own
trusty cayuse.

A full-text search of the OED found no case of CAYOOSH. If anybody has
documented and precisely transcribed quots. with that spelling, I'd be
happy to submit them to Oxford.

I don't want to get in over my head here, but the essence of the OED is
such quotations--which are arranged chronologically in each entry--and
the editors are always grateful for submissions from the public,
especially of quots. that represent words not in the Dictionary, or that
antedate the earliest OED quot. or help refine definitions or
etymologies. So, if you think you have a live one, please feel free to
send it to me.
--
Alan H. Hartley
119 West Kent Road
Duluth MN 55812-1152
U.S.A.
218/724-5095
http://www.d.umn.edu/~ahartley/