1 [uncountable and countable]MIan illness which affects a person, animal, or plantCOLLOCATIONS COLLOCATIONS have/suffer from a disease heart/liver/brain etc disease a disease of the brain/stomach etc catch a disease contract a diseaseformal (=catch a disease) a disease spreads/the spread of a disease infectious/contagious disease (=one that spreads quickly from one person to another) a fatal/deadly disease (=one that causes death) an incurable disease (=one that cannot be cured) a degenerative disease (=one that gradually gets worse and worse) a cure for a disease the symptoms of a disease (=the things that show that someone has it)
2 [countable]MISSsomething that is seriously wrong with society or with someone's mind, behaviour etc:
Loneliness is a disease of our urban communities.
a diseased plant
WORD CHOICE: WORD CHOICE: illness, diseaseIllness and disease are often used in the same way and are equally common in spoken English. However, illness is more often used to refer to the length of time or state of being unwell• He died after a long illness. • if you are off school because of illness!! Do not use illness to talk about less serious problems such as headaches or colds.Disease is a particular kind of illness, especially one that spreads from one person to another or affects a particular part of your body• infectious diseases • heart disease!! Disease can also be used to mean a lot of different diseases• Cigarette smoking causes death and disease. ➔ See alsoillness
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.