Secundo mi Webster's:

gringo  n  , pl  gringos [Sp, alter. of griego Greek, stranger, fr. L Graecus Greek] (1849) : a foreigner in Spain or Latin America esp. when of English or American origin; broadly : a non-Hispanic person ¦ often used disparagingly.

gringo n, pl. gringos [Espaniol, alteration de griego Greek, estraniero, del
L. Graecus [greco] (1849): un estraniero in espania o america latin, special-
mente quando de origine anglese o american; generalmente: un gente non-
hispanic, sovente empleate in un maniera denigrante.

Stan Mulaik