The Spanish word "queso" (meaning "cheese") comes from the Latin word "caseus", which also meant "cheese". The word evolved through Medieval Spanish "caisu" and Old Spanish "queisu" before reaching its modern form. This evolution shows a typical pattern in Spanish where the Latin 'ca-' sound often shifted to 'que-', and the internal '-s-' remained stable throughout the word's history.

The word "quesadilla" is a common derivative of "queso", literally meaning "little cheesy thing". Another related word is "quesero" meaning "cheese maker" or "cheese seller". These words maintain the "ques-" root from "queso" while adding different suffixes to create new meanings.

The English word "cheese" is actually related to "queso", as both come from the same Latin root "caseus". While Spanish maintained a form closer to the original Latin with the 'qu-' sound, English underwent different sound changes resulting in 'ch-'. Other English words derived from the same root include "casein" (the main protein found in cheese) and "cheesy".