Deadly

Capable of causing death; mortal; fatal; destructive; certain or likely to cause death; as, a deadly blow or wound.

Aiming or willing to destroy; implacable; desperately hostile; flagitious; as, deadly enemies.

Subject to death; mortal.

In a manner resembling, or as if produced by, death.

In a manner to occasion death; mortally.

In an implacable manner; destructively.

Extremely.