Which term describes the ability of an organism to resist infection or disease?

The term that describes the ability of an organism to resist infection or disease is immunity. Immunity refers to the mechanisms that the body employs to defend itself against pathogens such as bacteria, viruses, and other foreign invaders. This can be achieved through innate immunity, which is present at birth and provides a general defense, as well as adaptive immunity, which develops over time as the organism encounters different pathogens and creates specific responses.

In the context of veterinary medicine, understanding immunity is crucial for protecting the health of animals through vaccinations, proper hygiene, and other health management practices. This encompasses both individual immune responses and the broader implications for herd health.

The other terms are related but do not specifically capture the concept of resisting infections. Sensitivity usually refers to the responsiveness of a body to a stimulus, resistance refers more generally to the capacity to withstand something adverse, and reactiveness relates to an organism's reaction to stimuli but does not specifically encompass immunity. Thus, immunity is the most accurate term for the ability to resist infection or disease.