Sickness (noun)

1. An illness or ailment.
2. The state of being ill or unwell.
3. A feeling of nausea or discomfort in the stomach.

Origin:

Sickness first recorded in the 14th century, it comes from the old english word sicness, meaning illness or ailment.

Examples:

1. He was suffering from a sickness.
2. The sickness spread quickly through the school.
3. She felt a sickness in her stomach.
4. The sickness was caused by the bacteria.
5. The sickness lasted for several days.