Mortal vs. fatal vs. letal
In Portuguese, the words mortal, fatal, and letal all convey the concept of being deadly, dangerous, or causing death, but they have specific nuances and distinct contexts where they are used. Here's an explanation of their meanings and usage, supported by examples.
Mortal
B1Mortal refers to something related to death in a general sense or something that can cause death but is often used with an emotional or dramatic emphasis. It can also refer to humans as mortal beings.
Ele teve uma doença mortal, mas conseguiu se recuperar.
(He had a life-threatening disease, but he managed to recover.)
Os humanos são seres mortais.
(Humans are mortal beings.)
Ela sentiu um medo mortal durante o ataque.
(She felt a mortal fear during the attack.)
Fatal
B1Fatal is used to describe something that causes or results in death in a definitive way or something that leads to irreversible or disastrous consequences. It often has a sense of inevitability.
O acidente foi fatal para os passageiros no carro.
(The accident was fatal for the passengers in the car.)
A decisão de ignorar o aviso foi um erro fatal.
(The decision to ignore the warning was a fatal mistake.)
Uma overdose pode ser fatal se não tratada a tempo.
(An overdose can be fatal if not treated in time.)
Letal
B2Letal specifically conveys the concept of being highly dangerous and capable of causing death, particularly in a technical or scientific context such as poisons, weapons, or chemicals.
Este veneno é letal mesmo em pequenas doses.
(This poison is lethal even in small doses.)
Uma arma letal foi encontrada na cena do crime.
(A lethal weapon was found at the crime scene.)
A combinação de certos medicamentos pode ter um efeito letal.
(The combination of certain medications can have a lethal effect.)
Summary
In summary, mortal emphasizes the vulnerability of human life or has a dramatic/emotional tone, fatal suggests something that causes a definitive or inevitable outcome, often death, and letal specifically refers to substances, weapons, or actions capable of directly causing death in a clinical or technical sense. Their differences lie in their context and focus.