The Spanish word 'maligno' comes from the Latin word 'malignus', meaning 'evil by nature'. The Latin word itself is a combination of two elements: 'malus' meaning 'bad, evil' and the root '-gn-' meaning 'birth, origin'. When combined, these elements created a word that literally meant 'evil from birth' or 'evil by nature', which evolved into the modern Spanish word meaning 'malignant' or 'evil'.

Some related Spanish words that share the 'mal-' root include 'malo' (bad), 'mal' (evil, wrong), and 'maldad' (wickedness). These words all derive from the same Latin root 'malus' meaning 'bad, evil'.

English speakers might recognize the connection to words like 'malign', 'malignant', and 'malicious', which all share the same Latin ancestor 'malus'. The medical term 'malignant' (as in malignant tumor) and 'maligno' are particularly close cognates, both referring to something harmful or evil in nature. Other related English words include 'malevolent', 'maleficent', and 'malware', all carrying the sense of badness or evil from the Latin 'malus'.