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 formsharm·ful·ly, adverbharm·ful·ness, nounqua·si-harm·ful, adjectivequa·si-harm·ful·ly, adverbun·harm·ful, adjectiveun·harm·ful·ly, adverb

Synonyms for harmful

Antonyms for harmful

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for harmfulness

Historical Examples of harmfulness

  • 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.

  • The immorality and harmfulness of this system are obvious, and they spread with the extension of capitalism.

  • 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

British Dictionary definitions for harmfulness



causing or tending to cause harm; injurious
Derived Formsharmfully, adverbharmfulness, 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

Word Origin and History for harmfulness



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

Online Etymology Dictionary, © 2010 Douglas Harper