Noun sickness has 2 senses
  1. illness, unwellness, malady, sickness - impairment of normal physiological function affecting part or all of an organism
    --1 is a kind of ill health, unhealthiness, health problem
    --1 has particulars:
     ague; amyloidosis; anuresis, anuria; catastrophic illness; collapse; decompression sickness, aeroembolism, air embolism, gas embolism, caisson disease, bends; food poisoning, gastrointestinal disorder; lead poisoning, plumbism, saturnism; disease; hypermotility; indisposition; ozone sickness; toxemia of pregnancy, toxaemia of pregnancy, toxemia, toxaemia; growth
  2. nausea, sickness - the state that precedes vomiting
    --2 is a kind of symptom
    --2 has particulars:
     motion sickness, kinetosis; morning sickness; queasiness, squeamishness, qualm