I. ˈdethlē, -li adjective
Etymology: Middle English dethlich deadly, mortal, from Old English dēathlīc mortal, from dēath death + -līc -ly
1. : deadly , fatal , mortal , destructive
2. : like or having the characteristics of death
a deathly stillness
3. : of, relating to, or suggestive of death
I marked each deathly change in him — Robert Browning
Synonyms: see deadly
II. adverb
: in a way or to a degree resembling or approximating death
deathly sick