unhealthy

unhealthy — adjective

1. describes food, habits, or conditions that are likely to damage your body or mak

1.adjectiveA2
Definition

describes food, habits, or conditions that are likely to damage your body or make you ill.

Example

Theo stopped eating unhealthy food after his doctor warned him about heart disease.

collocation: unhealthy food / unhealthy diet

Working twelve-hour shifts without breaks created an unhealthy environment at the factory.

collocation: unhealthy environment / unhealthy conditions

Common collocations
  • unhealthy food
  • unhealthy diet
  • unhealthy lifestyle
  • unhealthy habits
  • unhealthy eating
  • unhealthy environment
  • unhealthy air
  • unhealthy living conditions
Synonyms
  • harmful

    more general; can apply to any kind of damage, not just health

  • damaging

    implies lasting or serious harm to the body

  • bad for you

    more informal, common in everyday speech

Antonyms
  • healthy

    the direct opposite; good for your body

  • nutritious

    used specifically for food that provides nourishment

  • beneficial

    formal; describes something that has a positive effect

Grammar Patterns

unhealthy + noun

link verb + unhealthy

Usage Note

This is the most common meaning of 'unhealthy'. It often appears before nouns such as 'diet', 'lifestyle', 'habit', 'food', and 'environment'.

Common Mistakes

Smoking is unhealthy for your health.
Smoking is unhealthy.
'unhealthy' already means bad for health; adding 'for your health' is redundant.

2. showing signs of poor physical condition; looking or feeling weak instead of bei

2.adjectiveB1
Definition

showing signs of poor physical condition; looking or feeling weak instead of being fit and well.

Example

After months of poor sleep, Christopher looked pale and unhealthy.

link verb + unhealthy: look / seem / appear unhealthy

The puppy was unhealthy when Alessia adopted it, but good care made it stronger.

Common collocations
  • look unhealthy
  • seem unhealthy
  • appear unhealthy
  • unhealthy skin
  • unhealthy complexion
  • unhealthy appearance
  • unhealthy pallor
Synonyms
  • sickly

    specifically describes someone who often looks or feels ill

  • weak

    broader meaning; can refer to physical strength or lack of energy

  • frail

    emphasises physical fragility, often due to age or illness

Antonyms
  • healthy

    in good physical condition

  • fit

    physically strong and in good shape, often through exercise

  • strong

    having physical power and energy

Grammar Patterns

link verb + unhealthy

unhealthy + noun (body part)

Usage Note

Predicative use after linking verbs (look, seem, appear, be) is more common than attributive use before a noun for this sense.

Common Mistakes

I am feeling unhealthy today' (when you have a cold).
I am feeling unwell today
'unhealthy' describes a longer-term condition or appearance, not a temporary illness.

3. describes thoughts, feelings, or social situations that are emotionally damaging

3.adjectiveB2
Definition

describes thoughts, feelings, or social situations that are emotionally damaging and outside what is considered psychologically balanced.

Example

An unhealthy obsession with checking his phone every two minutes was affecting Asher's sleep.

collocation: unhealthy obsession / unhealthy interest

The relationship became unhealthy when Omar stopped letting his partner see friends.

collocation: unhealthy relationship

Common collocations
  • unhealthy relationship
  • unhealthy obsession
  • unhealthy atmosphere
  • unhealthy competition
  • unhealthy attachment
  • unhealthy interest
Synonyms
  • abnormal

    more neutral; describes something that deviates from what is usual

  • dysfunctional

    used specifically for relationships or systems that are not working properly

  • toxic

    stronger; implies active harm, especially in relationships

Antonyms
  • healthy

    normal and balanced, especially in relationships

  • normal

    conforming to a standard; usual and expected

  • balanced

    emotionally or mentally stable; not extreme

Grammar Patterns

unhealthy + noun (abstract)

link verb + unhealthy (figurative)

Usage Note

Subject is usually an abstract noun such as 'relationship', 'atmosphere', 'obsession', 'interest', or 'attachment'. This sense applies only to psychological or social contexts, not physical health.

Common Mistakes

Their friendship is unhealthy because they argue sometimes.
Their friendship is unhealthy because one person controls the other completely.
'unhealthy' in this sense describes a serious imbalance, not minor disagreements.

Word family

  • health
    nounA1
  • healthy
    adjectiveA1
  • healthily
    adverbB1
  • unhealthily
    adverbB2
  • unhealthiness
    nounC1

Synonym discussion

Sense: adjective/1

'Unhealthy' is the most common word for things that damage your body — food, habits, or living conditions. 'Harmful' is broader and can apply to any kind of damage (physical, mental, environmental), not just health. 'Damaging' emphasises lasting or serious harm that weakens something over time. 'Detrimental' is more formal and is often used in academic or professional writing — for example, 'a detrimental effect on the economy'. 'Bad for you' is the everyday, informal equivalent, common in spoken English: 'Sitting all day is bad for you.' Choose 'unhealthy' when the harm is specifically about physical health; use 'harmful' or 'damaging' when the target is broader.

unhealthy ↗harmful ↗damaging ↗detrimental ↗bad for you

Common collocations

Adverbs

  • extremely unhealthy
  • deeply unhealthy
  • very unhealthy
  • increasingly unhealthy

Prepositions

  • unhealthy for

Etymology

Old EnglishEnglish

Formed by adding the prefix 'un-' (meaning 'not') to 'healthy'. 'Healthy' comes from Old English 'hǣlþ' (meaning wholeness, soundness, or wellness) combined with the suffix '-y' (meaning 'having the quality of'). The word 'unhealthy' has been in use since the late 1500s to describe anything that lacks health or damages well-being.