The word 'thirst' originates from the Old English noun 'þurst' or 'þyrst', which itself evolved from the Proto-Germanic þurstuz. This Germanic root is connected to the Proto-Indo-European (PIE) root ters-, meaning "dry". The semantic journey is direct and vivid: the core concept of "dryness" naturally extended to describe the physical sensation caused by a lack of moisture in the body. Over time, this concrete physical meaning was metaphorically applied to express any intense, consuming desire, paralleling the body's craving for water. Thus, the word's logic flows from an ancient state (dryness) to a physical feeling, and finally to an abstract yearning.

The word 'thirst' is a simplex word derived from a single, tight Germanic root. It is not productively formed from smaller, independent morphemes in modern English.