Ill"ness (?), n. [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."

• A instance of a disease.
  
• A person's perception of having poor health.