Are lethal and fatal the same? What about mortal? Or terminal? Deadly?
Although the words are close in definition, there are distinctions. If a weapon is lethal, it is capable of inflicting death. If it is fatal, it has been successful. The fatal blow is the killer. If the blow is only lethal, the victim might yet survive. Mortal means nearly the same as lethal, destructive of life, capable of inflicting death. Mort comes from Middle French mort, death. If something (namely, us) is mortal, then it is capable of death or dying. Deadly weapons tend to (and are meant to) kill, but the result isn’t inevitable.
However, should a Scot tell you someone is mortal, it is most likely to mean that person has imbibed too much and is dead drunk.
In writing a murder mystery, it is correct to say she drank a lethal poison and survived to tell the story. Deadly works there, as well. However, if the poison was fatal, she won’t be the one to talk about it later. If you use it that way, your reader may laugh about it.
Terminal means (among many definitions) coming to the end or leading to the end of life. A terminal patient is in the final stages of a fatal disease.
If I don’t stop now, 2014 will also be at an end and I won’t have the opportunity to wish you a productive, peaceful, joyful, HAPPY NEW YEAR!