deadly - definition and synonyms

 
adjective 

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/ˈdedli/
adjectivedeadly
comparativedeadlier
superlativedeadliest
  1. 1
    able or likely to kill people

    This is a potentially deadly disease.

    deadly to:

    Too many water changes can prove deadly to these delicate fish.

    a deadly weapon:

    The police charged him with possession of a deadly weapon.

  2. 2
    [only before noun] complete
    deadly silence:

    A deadly silence followed her announcement.

    a deadly secret:

    Don’t say anything to anyone – this is meant to be a deadly secret.

    in deadly earnest (=completely seriously):

    It started as a joke, but soon they were fighting in deadly earnest.

  3. 3
    informal very boring

    Some of our lectures were pretty deadly!

  4.   From our crowdsourced Open Dictionary
    5
    something that is deadly is fantastic or as good as it possibly can be

    That teacher is deadly! That was a deadly class.

    Submitted by Marg from Australia on 08/08/2009