In economics, a person who is able and willing to work yet is unable to find a job is considered unemployed. The unemployment rate measures the number of unemployed workers as a proportion of the total civilian labor force, where the latter includes both the unemployed and those with jobs (all those willing and able to work for pay).
Additional meaning of Unemployment:
Though most people care about the number of unemployed (8.2 million in the U.S. in April 2004), economists typically focus on the unemployment rate (5.6 percent). This corrects for the normal increase in the number of people working for pay or seeking work due to population increases and increases in the paid labor force relative to the population -- and thus the normal increase in the number of unemployed workers.