Meaning & use
harmful
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Meaning
adjectivecomparable
Likely to hurt people, damage things, or have a bad effect on health or the environment.
Grammar: Used before a noun or after a verb, often with to: harmful chemicals, harmful to children.
Patterns
- harmful to someone
- harmful to something
- harmful for someone
Too much sun can be harmful to your skin.
The company was fined for releasing harmful chemicals into the river.
Spreading false rumors is a harmful habit in any workplace.
Word forms
| comparative | more harmful |
|---|---|
| superlative | most harmful |
Common combinations
- harmful effects
- Doctors warned about the harmful effects of smoking.
- harmful to health
- Excess sugar is harmful to health.
- potentially harmful
- The test found a potentially harmful bacteria in the water.
- harmful substances
- Workers must wear masks around harmful substances.
Synonyms and how they differ
- damaging
- Damaging stresses lasting loss or injury, often to reputations or systems.
- toxic
- Toxic is narrower: it means poisonous.
- detrimental
- Detrimental is more formal and suggests a negative effect on progress or well-being.
Opposites
Word family
Commonly confused: harmful or harmful vs harmless?
harmful vs harmful vs harmless
Harmful causes damage; harmless does not. The suffixes -ful and -less give opposite meanings.
Practice
Which sentence uses the correct preposition?
Choose one answer.
Harmful is followed by to (or sometimes for) before the thing affected. Of, at and with do not fit this pattern.
Make it your own
Write a sentence using “harmful”, then check it and compare it with the examples above.