Sensitivity and specificity

This definition of medical test is always a puzzle to me.I always get confused when trying to explain to another person.
Today i just read again the definition of it. It may give some help to you.

Sensitivity:
definition:probability of a positive test when the disease is present.
application:if the test has a high sensitivity, it will identify patients with the disease, and therefore a negative result indicates that the patient doest not have the disease.

Specificity:
definition:probability of a negative test when the disease is absent.
application:if the test has a high specificity, a negative result identifies people who do not have the disease , and therefore a positive result indicates that the patient has the disease.