deadlier

adjective deadlier, deadliest

1. causing death or likely to cause death: a deadly poison
2. to the death; mortal or implacable: deadly combat, deadly enemies
3. typical of death: deadly pallor
4. very harmful; destructive
5. 1. extreme or excessive: deadly silence
   2. out-and-out; utter: with deadly gravity
6. oppressively tiresome: a deadly bore
7. perfectly accurate: deadly aim
8. Theol. causing spiritual death: the seven deadly sins

Origin: ME dedlich < OE deadlic: see dead & -ly

adverb deadlier, deadliest

1. in a way suggestive of death: to lie deadly still
2. extremely or excessively: deadly serious