Disease meaning : An abnormal condition of a human, animal or plant that causes discomfort or dysfunction; distinct from injury insofar as the latter is usually instantaneously acquired. (by extension) Any abnormal or harmful condition, as of society, people's attitudes, way of living etc. Lack of ease; uneasiness; trouble; vexation; disquiet. To cause unease; to annoy, irritate. To infect with a disease.