1. a stupid or careless mistake

1. to make a stupid or careless mistake
2. to move clumsily or without direction

Examples

• The accountant’s blunder cost the company thousands of dollars.
• It was a major blunder to forget the presentation materials.
• She blundered by sending the email to the wrong person.
• He blundered through his speech without preparation.
• The hiker blundered through the dark forest without a flashlight.
• Don’t blunder into making the same mistake twice.
• The team’s defensive blunder led to the opposing goal.