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

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Contemporary Examples of harmful

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British Dictionary definitions for harmful



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 harmful

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

Online Etymology Dictionary, © 2010 Douglas Harper