1

deadly

adjective dead·ly \ ˈded-lē \
Updated on: 10 Dec 2017

Definition of deadly

deadlier; deadliest
1 : likely to cause or capable of producing death
  • deadly poison
2 a : aiming to kill or destroy : implacable
  • a deadly enemy
b : highly effective
  • a deadly exposé
c : unerring
  • a deadly marksman
d : marked by determination or extreme seriousness
3 a : tending to deprive of force or vitality
  • a deadly habit
b : suggestive of death especially in dullness or lack of animation
  • deadly bores
  • a deadly conversation
4 : very great : extreme

deadliness

noun

Examples of deadly in a Sentence

  1. the world's most deadly snake

  2. a more deadly form of the disease

  3. They launched a deadly attack.

  4. Officers are allowed to use deadly force if necessary.

  5. She shoots with deadly accuracy.

  6. a basketball player with deadly aim

  7. A deadly silence followed his question.

  8. The two gang leaders are deadly enemies.

  9. He spoke with deadly seriousness.

Recent Examples of deadly from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'deadly.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of deadly

before 12th century

Synonym Discussion of deadly

deadly, mortal, fatal, lethal mean causing or capable of causing death. deadly applies to an established or very likely cause of death.
    • a deadly disease
mortal implies that death has occurred or is inevitable.
    • a mortal wound
fatal stresses the inevitability of what has in fact resulted in death or destruction.
    • fatal consequences
lethal applies to something that is bound to cause death or exists for the destruction of life.
    • lethal gas

2

deadly

adverb

Definition of deadly

1 archaic : in a manner to cause death : mortally
2 : suggesting death
3 : extremely
  • deadly serious

Examples of deadly in a Sentence

  1. I'm deadly serious about making an offer on the house.

Recent Examples of deadly from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'deadly.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of deadly

before 12th century


DEADLY Defined for English Language Learners

deadly

adjective

Definition of deadly for English Language Learners

  • : causing or able to cause death

  • : extremely accurate and effective

  • : extreme or complete


deadly

adverb

Definition of deadly for English Language Learners

  • : extremely or completely


DEADLY Defined for Kids

1

deadly

adjective dead·ly \ ˈded-lē \

Definition of deadly for Students

deadlier; deadliest
1 : causing or capable of causing death
  • deadly poisons
2 : meaning or hoping to kill or destroy
  • deadly enemies
3 : very accurate
  • He shot the arrow with deadly aim.
4 : 1extreme 1

Synonym Discussion of deadly

deadly, mortal, and fatal mean causing or capable of causing death. deadly is used of something that is certain or very likely to cause death.
    • The mushroom contains a deadly poison.
mortal is used of something that already has caused death or is about to cause death.
    • He received a mortal wound in battle.
fatal is used when death is certain to follow.
    • The wounds proved to be fatal.

2

deadly

adverb

Definition of deadly for Students

1 : in a way suggestive of death
  • Her face was deadly pale.
2 : to an extreme degree
  • deadly dull

Medical Dictionary

deadly

adjective dead·ly \ ˈded-lē \

medical Definition of deadly

deadlier; deadliest
: likely to cause or capable of causing death
  • a deadly disease
  • a deadly poison
  • a deadly instrument

deadliness

play \-nəs\ noun

Law Dictionary

deadly

adjective dead·ly

legal Definition of deadly

deadlier; deadliest
: likely to cause or capable of causing death; also : dangerous 2
Note: Deadly and dangerous are sometimes used interchangeably, especially in connection with weapons or instruments.


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