Lethal refers to anything dangerous enough to cause death. The cobra's venom is so lethal that if you get bitten and can't find the antidote, it's lights out forever. A co-op horror about scavenging at abandoned moons to sell scrap to the Company. lethal (comparative more lethal, superlative most lethal) Of, pertaining to, or causing death; deadly; mortal; fatal. LETHAL meaning: 1. able to cause or causing death; extremely dangerous: 2. able to cause or causing death…. Learn more. Synonyms for LETHAL: deadly, fatal, poisonous, infectious, infective, killer, harmful, toxic; Antonyms of LETHAL: healthy, nonlethal, beneficial, healthful, nonfatal. At LETHAL Corporation it is our objective to bring people back to the forefront of why they possess arms – why they should train regularly – why they should carry weapons every day – and why lethality, in certain life-threatening situations, is the capability to be desired rather than vilified. LETHAL definition: 1. able to cause or causing death; extremely dangerous: 2. able to cause or causing death…. Learn more. Define lethal. lethal synonyms, lethal pronunciation, lethal translation, English dictionary definition of lethal. adj. 1. Causing or capable of causing death: a lethal weapon. See Synonyms at fatal. 2. Extremely harmful; devastating: accusations lethal to the. LETHAL definition: of, relating to, or causing death; deadly; fatal: a lethal dose. See examples of lethal used in a sentence. The meaning of LETHAL is of, relating to, or causing death. How to use lethal in a sentence. Synonym Discussion of Lethal.