Which term best describes actions taken to lessen the impact of a vulnerability?

The term that best describes actions taken to lessen the impact of a vulnerability is "countermeasure." Countermeasures are strategies, mechanisms, or actions implemented to reduce the risk associated with vulnerabilities. They can be technical controls, such as firewalls and encryption, or administrative measures, like policies and training, designed to mitigate potential threats and their consequences.

Countermeasures aim not only to address existing vulnerabilities but also to bolster an organization's overall security posture against future threats. This proactive approach helps minimize the likelihood or severity of security incidents, enabling organizations to maintain their operations and protect vital assets even when vulnerabilities exist.

While other terms like prevention or response may seem relevant, "countermeasure" is the most encompassing term for actions taken specifically to mitigate the effects of vulnerabilities, rather than focusing solely on preventing incidents or responding to ones that have already occurred.