The Spanish verb 'pisar' (meaning 'to step on' or 'to tread') comes from the Vulgar Latin word 'pinsare', which itself derived from Classical Latin 'pinsere'. Both Latin words meant 'to pound' or 'to crush'. The semantic evolution from 'pounding/crushing' to 'stepping on' is quite intuitive, as the action of stepping firmly on something can be seen as a form of pounding or crushing with one's foot. The phonetic development involved the simplification of the consonant cluster 'ns' to just 's', which was a common sound change in the evolution from Latin to Spanish.

Some related Spanish words include 'pisada' (footstep), 'pisotear' (to trample), and 'piso' (floor, story of a building). All these words share the same root and maintain connections to the basic meaning of stepping or treading on something.

While there aren't many common English words directly related to 'pisar', the Latin root 'pinsere' (to pound, crush) is distantly related to the English word 'pestle' (as in mortar and pestle), which comes from the same Proto-Indo-European root meaning 'to crush'. This connection makes sense as a pestle is a tool used for pounding and crushing ingredients.