adj.
Pronunciation: ' ded-l ē
Function: adjective
Inflected Form: dead · li · er ; -est
Date: before 12th century
1 : likely to cause or capable of producing death < deadly poison>
2 a : aiming to kill or destroy : IMPLACABLE <a deadly enemy> b : highly effective <a deadly exposé> c : UNERRING <a deadly marksman> d : marked by determination or extreme seriousness
3 a : tending to deprive of force or vitality <a deadly habit> b : suggestive of death especially in dullness or lack of animation < deadly bores> <a deadly conversation>
4 : very great : EXTREME
– dead · li · ness noun
synonyms DEADLY , MORTAL , FATAL , LETHAL mean causing or capable of causing death. DEADLY applies to an established or very likely cause of death <a deadly disease>. MORTAL implies that death has occurred or is inevitable <a mortal wound>. FATAL stresses the inevitability of what has in fact resulted in death or destruction < fatal consequences>. LETHAL applies to something that is bound to cause death or exists for the destruction of life < lethal gas>.