harmful

adjective
harm·​ful | \ ˈhärm-fəl How to pronounce harmful (audio) \

Definition of harmful

: of a kind likely to be damaging : injurious

Keep scrolling for more

Other Words from harmful

harmfully \ ˈhärm-​fə-​lē How to pronounce harmfully (audio) \ adverb
harmfulness noun

Examples of harmful in a Sentence

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

Recent Examples on the Web

The number of new U.S. measles cases continued to accelerate last week as health authorities race to curb the outbreaks and scientists who study the virus say measles may be more harmful than once believed. Betsy Mckay, WSJ, "Measles Cases Continue to Soar, Stirring Concern Over Long-Term Effects," 15 Apr. 2019 Alcohol is viewed fondly by much of the population, despite being more harmful than cannabis by almost any measure. Amber Senter, Marie Claire, "We Have to Acknowledge That CBD Use Is a Privilege," 11 Apr. 2019 And even if these off-target mutations aren’t harmful, research has shown that a mutation in the CCR5 gene can make people more susceptible to dying from the flu. Angela Chen, The Verge, "Flawed DNA editing of alleged ‘designer babies’ may have put their health at risk," 29 Nov. 2018 Advertising Of immediate concern is whether warmer water will allow harmful algae containing toxins to stay viable long enough for shellfish to eat them and pass toxins to marine mammals and people. Dan Joling, The Seattle Times, "Pace of Bering Sea changes startles scientists," 16 Apr. 2019 While the magnetosphere shields Earth from the harmful radiation within these particles, giant blobs of them can create disturbances that interfere with satellites and communications signals. David Grossman, Popular Mechanics, "How a Second Look At 40-Year-Old Studies Helped Explain Solar Wind," 6 Apr. 2019 Georgia is now the third state to pass this harmful restriction this month. Glamour, "Abortion Bans Are a Call to Action—Not a Reason to Give Up," 29 Mar. 2019 Like a highly addictive drug (minus the harmful side effects) the island is a place that hooks you after just one trip. Lindsay Silberman, Town & Country, "How St. Bart's Survived the Devastating Hurricanes of 2017," 10 July 2018 The second problem is emissions of harmful nitrogen oxides and particulates from vehicles. The Economist, "Heathrow’s third runway could be blown off course by pollution," 28 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'harmful.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of harmful

14th century, in the meaning defined above

Keep scrolling for more

Learn More about harmful

Dictionary Entries near harmful

harm's way

harman

harmattan

harmful

harmless

Harmolita

harmonia

Statistics for harmful

Last Updated

13 May 2019

Look-up Popularity

Time Traveler for harmful

The first known use of harmful was in the 14th century

See more words from the same century

Keep scrolling for more

More Definitions for harmful

harmful

adjective

English Language Learners Definition of harmful

: causing or capable of causing damage or harm

harmful

adjective
harm·​ful | \ ˈhärm-fəl How to pronounce harmful (audio) \

Kids Definition of harmful

: causing or capable of causing harm : injurious Keep harmful substances away from children.

Other Words from harmful

harmfully \ -​fə-​lē \ adverb

harmful

adjective
harm·​ful

Legal Definition of harmful

: of a kind likely to cause harm

Other Words from harmful

harmfully adverb
harmfulness noun

Keep scrolling for more

More from Merriam-Webster on harmful

Thesaurus: All synonyms and antonyms for harmful

Spanish Central: Translation of harmful

Nglish: Translation of harmful for Spanish Speakers

Britannica English: Translation of harmful for Arabic Speakers

Comments on harmful

What made you want to look up harmful? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

something valued as if it were money

Get Word of the Day daily email!

Test Your Vocabulary

Time Traveler Quiz: Which Word Came First?

  • time traveler quiz which word came first
  • Which came first?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!