I wrote the following etymology and note on several years ago (it can almost certainly be improved on or amplified):

borrowed from Mexican Spanish, plural of , borrowed from Nahuatl <*chīlaquilli,> from , stem of chili + <-aquilli,> noun derivative from the passive stem of “enter, fit in,” “cause to enter, insert”
This analysis of the Nahuatl word is from Ángel María Garibay Kintana, _En torno al español hablado en México_ (México, 1997), pp. 101-04. Garibay K. rejects as improbable the oft-repeated analysis of the word as + <ātl> “water” + “greens, vegetables” (as in, for example, José Ignacio Dávila Garibi, _Del nahuatl al español_, Tacubaya, 1939, pp. 88-89).

H-Net doesn't seem to allow for italics or small caps, hence the brackets. Comments welcome!
Jim Rader