The Spanish word 'moribunda' (feminine form of 'moribundo'), meaning 'dying' or 'about to die', comes from the Latin word 'moribundus'. The Latin term was formed by combining two elements: the verb 'mori' meaning 'to die' and the suffix '-bundus' meaning 'tending toward'. This suffix '-bundus' was used in Latin to create adjectives indicating a tendency or progression toward a state, so 'moribundus' literally meant 'tending toward death' or 'in the process of dying'.

Some related Spanish words that share the same Latin root 'mori' include 'morir' (to die), 'muerte' (death), and 'mortal' (mortal). These words are generally more common and might be more familiar to Spanish learners. They all carry the core meaning related to death or dying, with 'moribunda' specifically describing someone or something in the process of dying.

English speakers might recognize the connection to several English words that come from the same Latin root 'mori', such as 'mortal', 'mortality', 'mortuary', and 'morbid'. The word 'moribund' exists in English as well, with the same meaning as Spanish 'moribundo/a', though it's more formal or technical. These words all share the fundamental connection to death or dying, though some, like 'morbid', have developed additional meanings over time.