1. people who act as if they know everything; know-it-alls
Usage: informal; often derogatory

Examples

• The wiseacres in the back row kept interrupting the teacher with corrections.
• Don’t listen to those wiseacres who think they have all the answers.
• The meeting was full of wiseacres offering unsolicited advice.
• She rolled her eyes at the wiseacres who criticized her presentation.
• The coach ignored the wiseacres on the sidelines shouting instructions.
• Those wiseacres always act like they could do everyone’s job better.