1. the capacity to detect and discriminate. In signal detection theory, sensitivity is measured by d prime (d′).

2. the probability that results from a test will indicate a positive diagnosis given that the individual actually has the condition for which he or she is being tested. Compare specificity.

3. in physiology, the ability of a cell, tissue, or organism to respond to changes in its external or internal environment. Sensitivity is a fundamental property of all living organisms.

4. awareness of and responsiveness to the feelings of others.

5. susceptibility to being easily hurt or offended.