sickness-n; 3 Senses

Sense Number 1: illness, malady, state of poor health

Commentary: SICKNESS[+state][+physiological][+illness]
NOTE: refers to maladies and disease in individuals

This sickness is apparently being caused by contaminated produce.
Scuba divers who ascend too quickly can get decompression sickness.
She took a two-month leave of absence because of her sickness.

WordNet 3.0 Sense Numbers: 1

Sense Number 2: defective quality, unsoundness

Commentary: SICKNESS[+quality][+defectiveness]
NOTE: refers to an abstract pejorative quality of something

The sickness of his jokes alienated his co-workers from him.
The preacher talked about the great moral sickness of the people.

WordNet 3.0 Sense Numbers: 2

Sense Number 3: becoming nauseous

Commentary: SICKNESS[+state][+physiological][+nausea]
NOTE: refers to temporary states of nausea, not disease

There was a lot of sickness on the airplane during the extreme turbulence.
The child suffers from car sickness frequently.
Mary got motion sickness from riding the roller coaster.
Sally had bad morning sickness during her last pregnancy.

WordNet 3.0 Sense Numbers: 3