Final answer:
Virulence is the term that describes the power and ability of an organism to cause disease, indicating the degree to which a pathogen can affect its host.
Step-by-step explanation:
The term that describes the power and ability of an organism to cause disease is virulence. Virulence refers to the degree to which a pathogen is pathogenic, which means its ability to cause disease in the host. Pathogens with high virulence will generally lead to a disease state upon entering the body and may even cause severe symptoms or multi-organ failure in healthy individuals. Less virulent pathogens might only cause mild symptoms or may not cause any noticeable illness at all. The outcome of an infection is influenced by the complex interaction between a microbe's virulence factors and the host's immune defences.