The Spanish word 'cuarto' comes directly from the Latin word 'quartus', meaning 'fourth'. In Spanish, 'cuarto' retained this numerical meaning but also developed additional meanings. It can refer to a 'quarter' (as in a fourth part of something) and interestingly came to mean 'room' - possibly because medieval Spanish homes were often divided into four main spaces.

Other common Spanish words sharing this root include 'cuarta' (quarter, fourth part), 'cuarteto' (quartet), and 'cuartel' (quarters, barracks). All these words maintain a connection to either the concept of 'four' or to spaces/rooms.

English speakers can easily remember 'cuarto' by connecting it to several English words that come from the same Latin root 'quartus'. These include 'quarter', 'quartet', 'quart', and 'quarters' (meaning rooms or lodging). Notice how the English 'qu-' corresponds to the Spanish 'cu-' in these related words, a common pattern between the two languages.