The Spanish word 'molino' (meaning 'mill') comes from the Latin word 'molinum', which referred to a mill or grinding stone (specifically 'saxum molinum' meaning 'grinding stone'). This Latin term itself derives from the verb 'molere', which meant 'to grind'. The evolution from the Latin verb for grinding to the noun for the place or device where grinding happens shows a natural semantic development that has been preserved in Spanish.

Some related Spanish words include 'moler' (to grind), 'molido' (ground), and 'molienda' (grinding, milling). These words all share the same Latin root 'molere' and maintain the core concept of grinding or milling in their meanings.

English speakers might recognize the connection to words like 'mill', 'miller', and even 'meal' (in the sense of ground grain). These English words are actually cognates with the Spanish 'molino', as they all ultimately derive from the same Indo-European root related to grinding. The word 'molar' (the grinding teeth) also comes from this same Latin root 'molere'.