illness has definitions from the field of medicine
1
[ noun ] (medicine) impairment of normal physiological function affecting part or all of an organism

Used in print

(The New York Times,...)

Horton_Smith of Detroit , a former president of the Professional_Golfers_Association , will receive the Ben_Hogan_Trophy for his comeback following a recent illness .

(LeRoy Fothergill, "Biological Warfare", in Peter...)

The incubation_period of infectious_disease , plus a variable period of illness even before a lethal effect , render this weapon unsuitable for hand-to-hand encounter .

(Christopher Davis, First Family....)

Mr._McKinley examined everything with critical care , seeking something material to blame for his son 's illness .

*