The word 'squatter' is built upon the verb 'squat', which entered English from Old French with a sense of pressing down or crushing. The core physical action of crouching low to the ground, implied by 'squat', naturally extended metaphorically to describe the act of settling on land without title—one plants oneself firmly on the ground without formal right. By adding the agent suffix '-er', the word concretely denotes the person who performs this action. Thus, the term logically progresses from a literal description of posture to a socio-legal category of unauthorized occupation.

Structure: squat (crouch, occupy) + er (agent suffix) - squat: From Middle English squatten, from Old French esquatir ("to crush, press down"), of Germanic origin, possibly imitative of the sound of something heavy falling flat. In this word, it functions as the core verb root meaning to crouch or to occupy a place without right. - er: A native English agent noun suffix from Old English -ere, of Germanic origin, used to form nouns denoting a person who performs the action of the verb.