unhealthy

un‧health‧y /ʌnˈhelθi/ BrE AmE adjective (comparative unhealthier, superlative unhealthiest)
[Word Family: noun: ↑health, ↑healthiness; adverb: ↑healthily ≠ ↑unhealthily; adjective: ↑healthy ≠ ↑unhealthy]
1. likely to make you ill:
unhealthy living conditions
2. not normal or natural and likely to be harmful:
an unhealthy relationship
unhealthy interest/obsession/fear etc
Gareth had an unhealthy interest in death.
3. not physically healthy SYN ill, sick:
an unhealthy baby
4. unhealthy skin, hair etc shows that you are ill or not healthy:
an unhealthy pale complexion

Oxford Advanced Learner's Dictionary

unhealthy

un·healthy [unhealthy unhealthier unhealthiest] [ʌnˈhelθi] [ʌnˈhelθi] adjective
1. not having good health; showing a lack of good health
• They looked poor and unhealthy.
• unhealthy skin

• His eyeballs were an unhealthy yellow.

2. harmful to your health; likely to make you ill/sick
• unhealthy living conditions

• an unhealthy diet/lifestyle

3. not normal and likely to be harmful
Syn: unwholesome
• He had an unhealthy interest in disease and death.
Opp: healthy
Derived Word: unhealthily
Example Bank:
• The miners worked in very unhealthy conditions.
• Doctors say too many teenagers adopt an unhealthy lifestyle.
• Just taking vitamin tablets will not turn an unhealthy diet into a good one.
• The unhealthy climate made it an unattractive place in which to settle.

• Tuberculosis often affects people in unhealthy living conditions.

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

unhealthy / ʌnˈhel.θi / adjective

B1 not good for your health, or not strong and well:

an unhealthy diet

unhealthily / -θɪ.li / adverb

Collins Advanced Learner’s English Dictionary

unhealthy

[ʌnhe̱lθi]
unhealthier, unhealthiest
1) ADJ-GRADED Something that is unhealthy is likely to cause illness or poor health.
  Avoid unhealthy foods such as hamburger and chips...
  He worked in the notoriously unhealthy environment of a coal mine.
  Ant:
  healthy
2) ADJ-GRADED If you are unhealthy, you are not very fit or well.
  I'm quite unhealthy really.
  ...a poorly dressed, unhealthy looking fellow with a poor complexion.
  Ant:
  healthy
3) ADJ-GRADED An unhealthy economy or company is financially weak and unsuccessful.
  The redundancy of skilled and experienced workers is a terrible waste and a clear sign of an unhealthy economy.
  Syn:
  weak
  Ant:
  strong
4) ADJ-GRADED If you describe someone's behaviour or interests as unhealthy, you do not consider them to be normal and think they may involve mental problems.
  Frank has developed what I would term an unhealthy relationship with these people...
  This government has a developed an unhealthy obsession with secrecy...
  MacGregor believes it is unhealthy to lead a life with no interests beyond politics.
  Ant:
  healthy

Merriam-Webster's Advanced Learner's Dictionary

unhealthy

un·healthy /ˌʌnˈhɛlɵi/ adj un·health·i·er; -est [or more ~; most ~] : not healthy: such as
a : not having or showing good health
• an unhealthy liver
• unhealthy workers
• Her skin looks blotchy and unhealthy.
b : harmful to your health : likely to make you sick
• unhealthy eating habits
• Tests revealed an unhealthy level of lead in the water.
• Eating honey can be unhealthy for babies.
c : not doing well : not successful
• an unhealthy economy
• a financially unhealthy company
d : involving or causing feelings and thoughts that are not normal and healthy
• He was stuck in an unhealthy relationship.
• She has an unhealthy interest in natural disasters.