harmful

[hahrm-fuhl]

adjective

1. causing or capable of causing harm; injurious.

   a harmful idea;

   a harmful habit.

   Synonyms: deleterious, damaging, detrimental, hurtful
   Antonyms: beneficial

harmful

/ ˈhɑːmfʊl /

adjective

1. causing or tending to cause harm; injurious

Other Word Forms

• harmfully adverb
• harmfulness noun
• quasi-harmful adjective
• quasi-harmfully adverb
• unharmful adjective
• unharmfully adverb

Word History and Origins

Origin of harmful¹

First recorded before 1000; Middle English; Old English hearmful; harm, -ful

Example Sentences

Kennedy has said he wants more studies on the COVID-19 shots, which he has long claimed are harmful — even deadly.

From Los Angeles Times

Is it harmful to maintaining that relationship with the material?

From Los Angeles Times

Though I knew my behaviors were harmful to myself and others, I could not stop compulsively repeating the same patterns.

From Los Angeles Times

The substance is supposed to be administered only by a physician, officials say, and patients who have taken the drug should be monitored by a professional because of its possible harmful effects.

From BBC

But in an email, he said that the tunnel “was among some of the least environmentally harmful options” for Last Chance Grade.

From Los Angeles Times

Related Words

• adverse 
• bad 
• catastrophic 
• damaging 
• destructive 
• detrimental 
• disadvantageous 
• disastrous 
• inimical 
• noxious 
• painful 
• pernicious 
• risky 
• ruinous 
• sinful 
• toxic 
• unhealthy 
• unsafe