Meaning of LETHAL in English
le ‧ thal /ˈliːθ ə l/ BrE AmE adjective
[ Date: 1500-1600 ; Language: Latin ; Origin: lethalis , from lethum 'death' , from letum (influenced by Greek lethe ; ⇨ ↑ lethargic ) ]
1 . causing death, or able to cause death ⇨ fatal :
a lethal dose of heroin
a lethal weapon
death by lethal injection
a lethal cocktail of drink and pills
These chemicals are lethal to fish.
2 . informal likely to be powerful or dangerous – often used humorously:
They were all drinking lethal amounts of tequila!
Higher taxes and higher inflation were a lethal combination.
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012