borrowed from Spanish, "cheese," going back to Latin cāseus — more at cheese entry 1.

Literally Spanish for “cheese,” as in, a quesadilla—queso typically refers to a hot cheese dip that is frequently eaten with tortilla chips. Mexican and Tex Mex restaurants often feature it on their appetizer menu, having figured out that many people enjoy eating straight cheese before, during, and after a meal.

Cheese, as well as the Spanish queso and German Kaese and a few other cheese words, all can be traced to the Latin word for cheese, caseus. Going back a little further, the earliest known proto-Indo-European root is *kwat-, a term that refers to the process of making cheese as it means “to ferment, to become sour.”