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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. 2017.
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Examples from the Web for harmfulness
Historical Examples
  • In the Middle Ages they thought to reduce its harmfulness at least by direct elimination, hence the use of drastic purgatives.

    Medieval Medicine

    James J. (James Joseph) Walsh
  • Quite possible, the experience, made at an early day with the breeding of animals, revealed the harmfulness of in-breeding.

    Woman under socialism August Bebel
  • The immorality and harmfulness of this system are obvious, and they spread with the extension of capitalism.

    Woman under socialism August Bebel
  • Many persons call almost every creature an insect that is small and supposed to be useless, or suspected of harmfulness.

  • They went from shop to shop, making the shopkeepers see the harmfulness of the Moncadist politics, promising them advantages.

    Csar or Nothing Po Baroja Baroja
  • This evidence regarding the physiological action of caffeol can not in any wise be construed to indicate a harmfulness of coffee.

    All About Coffee William H. Ukers
  • Most parents nowadays recognize the harmfulness of such a rgime, and are careful to feed their children on more stimulating fare.

    The Decoration of Houses Edith Wharton
  • But, in this order, notions of utility and of harmfulness are much less precise.

  • Neither Banter nor O'Flynn was a dangerous man; a little loud and exaggerated talk was the utmost extent of their harmfulness.

    A Girl Among the Anarchists Isabel Meredith
  • In this twentieth century, certain enlightened men are teaching the absurdity and harmfulness of a belief in a deity.

    The Necessity of Atheism Dr. D.M. Brooks
British Dictionary definitions for harmfulness


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 harmfulness



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

Online Etymology Dictionary, © 2010 Douglas Harper
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