According to the UK definition, the economically inactive are people not in employment who have not been seeking work within the last 4 weeks and/or are unable to start work within the next 2 weeks.

Economically inactive people are those who are neither employed nor unemployed; they’re not in paid full-time or part-time work, but they’re also not looking for a job or available to start work. You might be economically inactive for a number of reasons, such as being retired, a student or too ill to work perhaps because of a chronic condition.