illness vs. disease

Hey everyone, time for a quick lesson~! Today, I'll be talking about the difference between the words: illness & disease.

Illness n.

1. a. Poor health resulting from disease of body or mind; sickness.
   b. A disease. (http://www.thefreedictionary.com/illness)

Disease n.

1. A pathological condition of a part, organ, or system of an organism resulting from various causes, such as infection, genetic defect, or environmental stress, and characterized by an identifiable group of signs or symptoms.


2. A condition or tendency, as of society, regarded as abnormal and harmful. (http://www.thefreedictionary.com/disease) Example: Crime is a disease plaguing our cities!

Illness isn't used as often as disease, it sounds more formal and old fashioned. I guess in terms of usage, we are usually vague when we use illness. It seems to focus more on the condition of your body.

He's ill. (adj, old fashioned)

He has an illness that makes him tired all the time. (n.)

Disease seems like something has gone wrong with you because of a virus or bacteria. But, apparently can also refer to genetic problems and stress related issues. It is used more to focus on the thing which is attacking or weakening your body. It is often used in a specific way.

He has Parkinson's Disease.

Have you heard of Lou Gehrig's Disease?

Cancer is a disease that is a real problem these days.

Malaria is a tough disease to eradicate (get rid of).

We also have a more recent and casual word which has the same usage as illness:

Sickness n.

1. The condition of being sick; illness.


2. A disease; a malady.


3. Nausea. Ex: motion sickness, sea sickness


4. A defective or unsound condition. (http://www.thefreedictionary.com/sickness)

He has some kind of weird sickness that makes him tired all the time.

His sickness is getting worse.

He's really sick. (adj)

Any questions?

Phil