From Longman Dictionary of Contemporary Englishin actionin actionDOsomeone or something that is in action is doing the job or activity they are trained or designed to do photos of ski jumpers in actionsee/watch something/somebody in action I’d like to see the new computer system in action. → action
Examples from the Corpus
in action• It's a chance for students to see a court in action.• The advertisement shows two firefighters in action putting out a blaze.• I've heard a lot about his dancing - I'd love to see him in action.• I had seen him in action during the San Jose strike, and I was very impressed.• These photos show the ski jumpers in action.• a memorial to the thousands of soldiers killed in action 