likely to cause death [= lethal]:
a deadly poison
a deadly weapon
someone who will always be your enemy and will try to harm you as much as possible:
The two rapidly became deadly enemies.
complete or total:
We sat in deadly silence.
He was in deadly earnest (=completely serious).
causing harm in a very effective way:
She hit the target with deadly accuracy.
like death in appearance:
like death[only before noun]
His face had a deadly paleness.