Learner's definition of DISEASE
1 : an illness that affects a person, animal, or plant : a condition that prevents the body or mind from working normally
He suffers from a rare genetic disease.
a deadly/debilitating disease
a disease of the mind/kidneys
diseases of poultry
2 [count] : a problem that a person, group, organization, or society has and cannot stop
— diseased/dɪˈziːzd/adjective,[more diseased; most diseased]