Compañero (female, “compañera”) is Spanish for “companion” or “friend” or “pardner.” The term is used in western films and literature.
 
   
(Dictionary of American Regional English)
compañera n SW
A female companion, a mistress.
1844 (1846) Kendall Santa Fe Exped. 2.342, That the good padres of that country have their compañeras, or female companions, is well known.
 
compañero n. Also campanyero, companyero chiefly SW
A male companion, a pardner.
1845 Fremont Rept. Rocky Mts. 256, Four compañeros joined our guide at the pass.
1848 (1855) Ruxton Life Far West 147 NM, As several mountaineers were in company, Killbuck and LaBonte recognized more than one friend, and the former and Sublette were old compañeros.
1894 Dialect Notes 1.342 TX, Compañero: partner; corresponds in mining slang to “pardner,” “pard,” etc.
 
25 July 1829, Trumpet and Universalist Magazine, “Danger of Crossing the Andes,” pg. 16:
It was pointed out to me by the man who was with him when he died, who gazed at it a moment, then looking at me in the face, shook his head with much apparent feeling, lifted up his shoulders, and sighed “Probre companero,” poor companions—then as if stifling a sigh to his memory, lifted up his load and hastened forward.
 
13 February 1836, The Boston Pearl, “My Equestrian Trip to Lima,”  pg. 172:
I drank as deep as the best of them, and as I emptied glass after glass, I saw the eyes of my companeros lighted with the same sort of joy as that with which a gourmand regards the stuffing of a fat duck whose bones he hopes to pick.