Final answer:
A disease is a condition that impairs normal body function and can be caused by various factors such as genetics, pathogens, and environmental influences.
Step-by-step explanation:
An abnormal condition of all or part of the body, or its systems or organs, which makes the body incapable of carrying on normal function, is called a disease. A disease can arise from various causes such as infection, genetics, environmental factors, or an inappropriate immune response. Homeostatic imbalance can lead to diseases due to the failure of internal systems to maintain normal function, causing cells to lack necessities or accumulate toxic substances. Moreover, diseases can involve immunodeficiency, a condition where the immune system fails to respond adequately to threats, potentially due to genetic reasons or as a result of external factors such as infection or chemical exposure. Certain diseases also involve the malfunction of hormone-secreting glands or abnormal growth in parts of the body.