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[hahrm-fuh l] /ˈhɑrm fəl/
causing or capable of causing harm; injurious:
a harmful idea; a harmful habit.
Origin of harmful
before 1000; Middle English; Old English hearmful. See harm, -ful
Related forms
harmfully, adverb
harmfulness, noun
quasi-harmful, adjective
quasi-harmfully, adverb
unharmful, adjective
unharmfully, adverb
hurtful, detrimental, damaging, deleterious.
beneficial. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for harmful
Contemporary Examples
Historical Examples
  • Is it not a dreadful thing that one's mind should be thus ruined by a useless and harmful practice?

  • Corporal punishment of schoolboys is only useless and harmful brutality.

    The Sexual Question August Forel
  • Wine is harmful if taken with greedy lips, but if drunk in moderation it is wholesome.

    De Re Metallica Georgius Agricola
  • These are the persons who do the most harm in society, and introduce into it the most harmful taints.

    The Sexual Question August Forel
  • It is utterly worthless to God, and harmful to man; therefore, it must die.

    Sanctification J. W. Byers
British Dictionary definitions for harmful


causing or tending to cause harm; injurious
Derived Forms
harmfully, adverb
harmfulness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for harmful

mid-14c., from harm (n.) + -ful. Related: Harmfully.

Online Etymology Dictionary, © 2010 Douglas Harper
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