harmful

"Harmful" is a straightforward but very useful adjective in English. It has one core meaning, but it appears in many different contexts — from health and the environment to relationships and society. Understanding it well will help you use it confidently in both speaking and writing.

1adjectivecausing damage or injury

When something is harmful, it causes damage, injury, or a bad effect on someone or something. Think of it as the opposite of 'safe' or 'beneficial'. If something hurts you — physically, emotionally, or in any other way — it is harmful.

everyday language · Modern, widely used

Smoking is harmful to your health.

Too much screen time can be harmful to children.

Some cleaning products contain harmful chemicals, so always read the label.

2adjectivefigurativedamaging to society or relationships

You can also use 'harmful' to describe things that damage people's feelings, relationships, or society as a whole — not just physical harm. For example, spreading false information or saying cruel things can be described as harmful.

social and emotional contexts · Modern, widely used · figurative

Spreading rumors about someone is harmful to their reputation.

The report warned that the new policy could have harmful effects on low-income families.

Negative self-talk can be harmful to your confidence over time.

3adjectivedamaging to the environment

In environmental discussions, 'harmful' is used to describe things that damage nature, animals, or the planet. This is a very common use in news articles and scientific writing.

science and environment · Modern, widely used

Plastic waste is harmful to marine life.

The factory was releasing harmful gases into the atmosphere.

We should reduce our use of harmful pesticides in farming.