The Spanish word 'exento' (meaning 'exempt' or 'free from') comes from the Latin 'exemptus', meaning 'taken out' or 'removed'. This Latin word was derived from 'eximere' ('to take out, remove'), which was formed by combining two elements: the prefix 'ex-' meaning 'out of, from' and the verb 'emere' meaning 'to take, buy'. The evolution from 'taking out' to 'being exempt' reflects how something that is taken out or removed from a group is freed from whatever applies to that group.

Some related Spanish words include 'eximir' (to exempt or free from obligation) and 'exención' (exemption), which share the same Latin roots and maintain similar meanings around the concept of being freed from an obligation or rule.

English speakers might recognize the connection to words like 'exempt' and 'exemption', which come from the same Latin source 'exemptus'. The prefix 'ex-' is also very common in English, appearing in words like 'exit' (to go out), 'export' (to carry out), and 'exclude' (to shut out). Additionally, the Latin 'emere' (to take, buy) is found in English words like 'redeem' (to buy back) and 'premium' (literally something taken first).