ILLNESS
illness, unwellness, malady, sickness
(noun) impairment of normal physiological function affecting part or all of an organism
Source: WordNet® 3.1
Etymology
Noun
illness (countable and uncountable, plural illnesses)
(countable) An instance of a disease or poor health.
(uncountable) A state of bad health or disease.
Synonyms
• (instance): sickness
• (state): sickness
• See also disease
Source: Wiktionary
Ill"ness, n. Etym: [From Ill.]
1. The condition of being ill, evil, or bad; badness;
unfavorableness. [Obs.] "The illness of the weather." Locke.
2. Disease; indisposition; malady; disorder of health; sickness; as,
a short or a severe illness.
3. Wrong moral conduct; wickedness. Shak.
Syn.
– Malady; disease; indisposition; ailment.
– Illness, Sickness. Within the present century, there has been a
tendency in England to use illness in the sense of a continuous
disease, disorder of health, or sickness, and to confine sickness
more especially to a sense of nausea, or "sickness of the stomach."
Source: Webster’s Unabridged Dictionary 1913 Edition