The Spanish word 'testado' comes from the Latin verb 'testari', meaning 'to testify' or 'to make a will'. This evolved into the Spanish verb 'testar' (to make a will), and when combined with the past participle suffix '-ado', it forms 'testado', meaning 'testified' or 'willed'.

Some related and more common Spanish words include 'testigo' (witness), 'testimonio' (testimony), and 'testamento' (will, testament). All these words share the same Latin root 'testari' and relate to the concepts of witnessing, testifying, or making legal declarations.

English speakers might recognize the connection to words like 'testify', 'testimony', 'testament', and 'intestate'. These all come from the same Latin root 'testari'. While the Spanish 'testado' specifically relates to making a will or testifying, the English derivatives have broadened to include any form of giving evidence or making declarations, with 'testament' specifically preserving the connection to wills and final wishes.