As nouns the difference between flu and illness
is that flu is influenza while illness is (countable) an instance of a disease or poor health.
flu
English
(Influenza)
Alternative forms
* 'flu (dated), floo (dated)
Noun
(
en noun)
Influenza.
(informal) Common cold.
Synonyms
* (influenza) grippe, grip
Derived terms
* avian flu
* bird flu
* blue flu
* diplomatic flu
* Spanish flu
* stomach flu
* swine flu
illness
English
Noun
(countable) An instance of a disease or poor health.
(uncountable) A state of bad health or disease.
Synonyms
* (instance) sickness
* (state) sickness
* See also
Related terms
* ill
* hypochondriac
External links
*