If they're actively looking for work, then they're unemployed. If they're not looking for work because they assume there are no opportunities, they're "discouraged workers": https://www.investopedia.com/terms/d/discouraged_worker.asp. Discouraged workers aren't counted in the primary unemployment rate, but are counted in U4 and U6, which are also historically low; see https://fred.stlouisfed.org/series/U4RATE and https://fred.stlouisfed.org/series/U6RATE.