The Spanish word 'heredero' (meaning 'heir') comes from the Latin word 'hereditarius', meaning 'relating to inheritance'. It was formed by combining the Spanish verb 'heredar' (to inherit) with the agent suffix '-ero', which is commonly used in Spanish to indicate a person who performs an action or is associated with something. So literally, a 'heredero' is 'one who inherits' or 'one who is related to inheritance'.

Some related Spanish words that might be easier to remember include the verb 'heredar' (to inherit), 'herencia' (inheritance), and 'hereditario' (hereditary). All these words share the same Latin root and form a family of words related to inheritance and succession.

English speakers might recognize the connection to words like 'hereditary', 'heritage', and 'inherit', which all come from the same Latin root. The English word 'hereditary' is particularly close to the original Latin 'hereditarius' and maintains a very similar meaning, referring to characteristics or rights that are passed down from parent to child.