Definitions for "deadly"
Aiming or willing to destroy; implacable; desperately hostile; flagitious; as, deadly enemies.
In an implacable manner; destructively.
Capable of causing death; mortal; fatal; destructive; certain or likely to cause death; as, a deadly blow or wound.
Subject to death; mortal.
In a manner resembling, or as if produced by, death; deathly.
Keywords:  exceedingly, harmful
exceedingly harmful
Keywords:  violent, rapid, course, disease, effect
(of a disease) having a rapid course and violent effect
Keywords:  extremely