Lethal is a word that signifies something deadly or fatal, capable of causing death. There are several synonyms for this word that convey similar meanings, including deadly, fatal, lethal, mortal, poisonous, terminally ill, fatalistic, and life-threatening. These words can be used interchangeably to describe situations where there is a risk of death or injury. They are often used in discussions related to medicine, war, and other high-risk environments where the potential for death is significant. Regardless of the context, these words all communicate the same underlying message of danger and the potential for lethal consequences.