Blunder (noun)

1. A mistake or error in judgment, especially one that is serious or embarrassing.
2. A stupid or careless action or remark.

Origin:

The word is derived from the middle dutch word 'blundern' which means 'to blunder' or 'to make a mistake'.

Examples:

1. The company's financial blunder cost them millions of dollars.
2. The candidate's blunder during the debate may have cost him the election.
3. It was a simple blunder, but one that had far-reaching consequences.
4. He made a blunder by forgetting the CEO's name during the meeting.
5. The blunder was noticed by everyone in the room and was the source of much embarrassment.