harmful

IPA/ˈhɑːmfl/
KK[hˈɑrmfəl]IPA/ˈhɑːrmfl/

harmful — adjective

  • harmfulpositive
  • more harmfulcomparative
  • most harmfulsuperlative

1. likely to cause physical damage, health problems, or other negative effects to a

1.adjectiveB1
Definition

likely to cause physical damage, health problems, or other negative effects to a person, animal, or the environment

Example

Ada wears gloves when using the spray because the chemicals are harmful to her skin.

pattern: harmful to + body part / health

Kabir worried that the polluted air near the factory was harmful to his health.

collocation: harmful to health

Common collocations
  • harmful to health
  • harmful to the environment
  • harmful effects
  • harmful chemicals
  • harmful substances
  • harmful bacteria
  • potentially harmful
  • harmful habit
Synonyms
  • damaging

    stronger emphasis on physical or structural harm

  • dangerous

    broader meaning; implies risk of serious harm or injury

  • injurious

    more formal register; typically used in medical or legal contexts

  • detrimental

    formal; suggests long-term negative effects, often on health or progress

Antonyms
  • harmless

    the direct opposite; does not cause harm

  • safe

    broader meaning; free from risk or danger

Grammar Patterns

harmful + noun

be + harmful + to + noun phrase

Usage Note

Commonly followed by the preposition 'to' to specify who or what is affected, as in harmful to health, harmful to the environment, or harmful to children.

Common Mistakes

This food is harmful for your health.
This food is harmful to your health.
The correct preposition after 'harmful' is 'to', not 'for'.
He thinks the drug is harmless for patients.' (when meaning 'not harmful').
He thinks the drug is harmless to patients.
'Harmless' also takes 'to', not 'for'.

Word family

Synonym discussion

Sense: adjective/1

Harmful is the most general and widely used term among these words. It simply means something causes or can cause harm, whether to people, animals, or the environment. Dangerous implies a higher level of risk and often suggests the possibility of serious injury or death — a harmful chemical may irritate your skin, but a dangerous chemical could kill you. Damaging focuses on physical or structural harm that reduces value or function, such as a damaging storm. Injurious is more formal and typically appears in medical or legal writing (e.g., injurious behavior). Detrimental is also formal and emphasizes long-term negative effects, especially on health or progress. For everyday situations, harmful is the natural choice: "Too much sugar is harmful to your teeth."

harmful ↗dangerous ↗damaging ↗injurious ↗detrimental ↗

Etymology

Proto-GermanicOld EnglishMiddle EnglishEnglish

From Old English 'hearm' (hurt, injury, damage) combined with '-ful' (full of). The word 'harm' itself comes from Proto-Germanic *harmaz, related to Old Saxon 'harm', Old High German 'haram', and Old Norse 'harmr' (grief, sorrow). The suffix '-ful' turns nouns into adjectives meaning 'full of' or 'characterized by'. The modern spelling 'harmful' has been in use since at least the 14th century.