The Spanish word 'cumplido' (meaning 'fulfilled' or 'completed') comes from the verb 'cumplir' ('to fulfill' or 'complete'), which traces back to the Latin verb 'complere'. The Latin 'complere' was formed by combining two elements: the prefix 'com-' meaning 'together' or 'completely', and the verb 'plere' meaning 'to fill'. So literally, 'complere' meant 'to fill completely' or 'to complete', a meaning that has carried through to modern Spanish.

Some related Spanish words that might be more familiar to Spanish learners include 'cumplir' (to fulfill, to complete), 'cumpleaños' (birthday - literally the day when years are completed), and 'incumplido' (unfulfilled, incomplete). All these words share the basic idea of completion or fulfillment from their Latin root.

English speakers might recognize the connection to words like 'complete', 'complement', and 'accomplish', which all come from the same Latin root 'complere'. The 'ple-' element in these words (meaning 'to fill') is also found in English words like 'plenty', 'plenary', and 'replenish'. Understanding these connections can help remember that 'cumplido' relates to completion or fulfillment.