1 [count] a : an activity (such as singing a song or acting in a play) that a person or group does to entertain an audience ▪ This evening's performance will start at 8 o'clock. ▪ The hall is usually used for orchestra performances. —sometimes used figuratively ▪ That tearful apology was quite a performance—I almost believed you really were sorry. b : the way an actor performs a part in a play, movie, etc. ▪ The critics loved her performance as the villain. ▪ She gave a brilliant performance as the villain. [=she played the role of the villain brilliantly]
2 somewhat formal : the act of doing a job, an activity, etc. [noncount] ▪ the performance of procedures/activities/duties [singular] ▪ Event planners hope to avoid a repeat performance of last year's problems. [=hope that last year's problems will not happen again this year]
3 : how well someone or something functions, works, etc. : how well someone or something performs [count] ▪ A supervisor will evaluate each employee's performance. ▪ employees with strong job performances ▪ a student's academic performance ▪ The team's performance last night was poor. [=the team performed/played poorly last night] ▪ This car had the best overall performance. [=this car functioned better than all the other cars] ▪ How has the company's stock performance been? [=has the value of the company's stock been increasing/decreasing?] [noncount] ▪ She was fired for poor job performance. [=she was fired for doing her job badly] ▪ Employees are given an annual performance assessment/evaluation. ▪ The gas additive improves engine performance. ▪ an increased level of performance ▪ We've introduced new performance levels/standards. ▪ a bicyclist who was disqualified for taking performance-enhancing drugs [=drugs that improve your ability to do something] —see also high performance
4 [singular] Brit informal : an act that requires a lot of time and effort ▪ Getting to the airport turned out to be a real performance [=production] because of the bridge construction.