1. to reverse or cancel the effect of something
2. to unfasten or loosen something that has been tied, buttoned, or secured
3. to cause the ruin or downfall of someone or something
Usage: formal

Examples

• Press Ctrl+Z to undo your last action.
• She tried to undo the damage caused by her mistake.
• Can you help me undo this knot?
• He began to undo his tie after the long day.
• The scandal could undo years of hard work.
• Please undo the buttons on your shirt for the examination.
• One careless decision can undo a lifetime of achievements.