The Spanish word 'beso' (meaning 'kiss') comes from the Latin word 'basium', which specifically meant an 'erotic kiss' in Classical Latin. The word evolved through Late Latin, where it took the intermediate form 'baisu', before finally developing into the modern Spanish 'beso'. Unlike its Latin ancestor which had a more specific romantic or erotic connotation, the Spanish word 'beso' has broadened its meaning to refer to any kind of kiss, whether romantic, familial, or friendly.

The word 'beso' has given rise to several related Spanish words that Spanish learners might recognize. These include the verb 'besar' (to kiss), 'besito' (little kiss), and 'besote' (big kiss). All of these words maintain a clear connection to the basic meaning of 'kiss'.

While English doesn't have any common words directly related to 'beso', it's interesting to note that English historically had three different words for 'kiss' borrowed from different sources: 'kiss' (from Germanic origins), 'osculation' (from Latin 'osculari'), and 'buss' (possibly related to the Latin 'basium'). The casual word 'buss' meaning 'kiss', though now archaic, shows a distant connection to the same Latin root as Spanish 'beso'.