The Spanish word 'naftalina' (naphthalene) traces its origins back to the Ancient Greek word 'νάφθα' (naphtha), which referred to bitumen or petroleum. This Greek word was borrowed into Latin as 'naphtha', keeping its meaning of petroleum. The word then made its way into French as 'naphte', and later developed into 'naphtaline', referring specifically to the chemical compound naphthalene. Spanish finally borrowed this term from French, adapting it to 'naftalina', which refers to the white crystalline substance commonly used as mothballs.

The Spanish word 'nafta', meaning petroleum or naphtha, is a closely related and simpler word that shares the same Greek root. While 'naftalina' specifically refers to the crystalline chemical compound used as mothballs, 'nafta' retained the original meaning of petroleum or fuel.

English speakers might recognize the connection to the words 'naphtha' (a flammable oil) and 'naphthalene' (the chemical name for mothballs). These English words share the same Greek ancestor 'νάφθα'. While 'naphtha' maintained its original meaning related to petroleum products, 'naphthalene', like Spanish 'naftalina', specifically refers to the mothball compound derived from coal tar.