The Spanish word 'pozo' meaning 'well' comes from Late Vulgar Latin 'putium', which itself derives from Classical Latin 'puteus' meaning 'well' or 'vertical shaft'. The evolution from Latin to Spanish shows typical sound changes, where the Latin 't' became 'z' in Spanish (a process called lenition), and the Latin 'u' shifted to 'o'.

While 'pozo' itself is a relatively simple and common Spanish word, it has given rise to several related terms in Spanish. For example, 'pocero' means 'well-digger', and 'pozole' (a type of Mexican soup/stew) gets its name because it's traditionally prepared in a deep pot, reminiscent of a well.

While English doesn't have many common words directly related to Latin 'puteus', we do see it in some technical terms. The word 'pit' in English, though from a different Germanic root, serves a similar function in describing deep holes or shafts. The geological term 'puteal', meaning a well-curb or a stone enclosure around a well, is a rare English word that does come from the same Latin root as 'pozo'.