harmful

adjective

harm·​ful ˈhärm-fəl 

: of a kind likely to be damaging : injurious

harmfully

ˈhärm-fə-lē 

adverb

harmfulness noun

Synonyms

• adverse
• bad
• baleful
• baneful
• damaging
• dangerous
• deleterious
• detrimental
• evil
• hurtful
• ill
• injurious
• mischievous
• nocuous
• noxious
• pernicious
• prejudicial
• wicked

Examples of harmful in a Sentence

DDT has been proven to be extremely harmful to the environment.

Recent Examples on the Web

Working out prior to menopause will reduce the risk of osteoporosis in your later years. And avoid harmful habits – smoking and heavy alcohol consumption can weaken bone density and increase the risk of fractures. —Jianying Zhang, Discover Magazine, 8 Nov. 2024

Albanese cited the risks to the physical and mental health of children from excessive social media use, in particular the risks to girls from harmful depictions of body image and misogynist content aimed at boys. —Reuters, NBC News, 7 Nov. 2024

These remedies are incomplete at best and harmful at worst. —Thomas G. Moukawsher, Newsweek, 5 Nov. 2024

This may include protecting people’s privacy, mitigating harmful biases, improving transparency or reducing environmental impact—a very hot topic in the news recently. —Eric Miquelon, Forbes, 5 Nov. 2024

Word History

First Known Use

14th century, in the meaning defined above

Kids Definition

harmful

adjective

harm·​ful ˈhärm-fəl 

: causing damage : injurious

harmfully

-fə-lē 

adverb

harmfulness noun

Legal Definition

harmful

adjective

harm·​ful

: of a kind likely to cause harm

harmfully adverb

harmfulness noun