deadly

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Causing or tending to cause death: deadly weapons; a deadly spill of radioactive waste products. See Synonyms at fatal.
2. adj. Suggestive of death: a deadly pallor.
3. adj. Aiming or wanting to kill; implacable: deadly enemies.
4. adj. Destructive in effect: gave the film a deadly review.
5. adj. Tending to take away vitality, effectiveness, or force: the deadly habit of procrastination.
6. adj. Absolute; utter: deadly concentration.
7. adj. Extreme or terrible: worked under deadly strain.
8. adj. Extremely accurate; unerring: She is a deadly shot with the bow.
9. adj. Dull, tedious, and boring: a deadly prose style.
10. adv. So as to suggest death.
11. adv. To an extreme: deadly serious.

Century Dictionary and Cyclopedia

1. Mortal; liable to death; being in danger of death.
2. Occasioning or capable of causing death, physical or spiritual; mortal; fatal; destructive: as, a deadly blow or wound.
3. Mortal; implacable; aiming or tending to kill or destroy: as, a deadly enemy; deadly malice; a deadly feud.
4. Adapted for producing death or great bodily injury: as, a deadly weapon; a deadly drug.
5. Dead.
6. Very great; excessive.
7. Mortally.
8. Implacably; destructively.
9. In a manner resembling death; deathly: as, deadly pale or wan.
10. Extremely; excessively.

Wiktionary

1. adj. obsolete Subject to death; mortal.
2. adj. Causing death; lethal.
3. adj. by extension Very accurate (of aiming with a bow, firearm, etc.).
4. adj. informal Very boring.
5. adj. informal Excellent, awesome, cool.
6. adv. obsolete Fatally, mortally.
7. adv. In a way which suggests death.
8. adv. Extremely.

GNU Webster's 1913

1. adj. Capable of causing death; mortal; fatal; destructive; certain or likely to cause death.
2. adj. Aiming or willing to destroy; implacable; desperately hostile; flagitious.
3. adj. obsolete Subject to death; mortal.
4. adv. In a manner resembling, or as if produced by, death; deathly.
5. adv. In a manner to occasion death; mortally.
6. adv. In an implacable manner; destructively.
7. adv. obsolete Extremely.

WordNet 3.0

1. adj. of an instrument of certain death
2. adv. (used as intensives) extremely
3. adj. involving loss of divine grace or spiritual death
4. adv. as if dead
5. adj. extremely poisonous or injurious; producing venom
6. adj. exceedingly harmful
7. adj. (of a disease) having a rapid course and violent effect
8. adj. causing or capable of causing death