Grammar fix
serious illness
bad illness
An illness that is severe, dangerous, or could have major effects on your health.
collocationB1common
Hear it in context
Notice where the phrase sounds natural.
After being diagnosed with a serious illness, she had to spend several weeks in the hospital.
If a family member has a serious illness, it can affect everyone’s daily routine and emotional well-being.
Fix the pattern
One small grammar move makes it sound right.
Not: She has a heavy illness.
Say: She has a serious illness.
Illnesses are 'serious', not 'heavy' (heavy is about weight).
Which sounds natural?
Tap the one a native speaker would say.
'A serious illness' is the everyday phrase; 'a grave medical condition' is clinical/report-speak.
Build natural chunks
Words that usually travel with it.
a serious illness
- suffer from
- develop
- recover from
- life-threatening