Example: John's quixotic plan to save the world by himself was admirable, but ultimately unrealistic.

• Her quixotic dreams of becoming a famous actress seemed unattainable to her friends.
• The politician's quixotic promises left the public skeptical.
• The quest for a utopian society can often be seen as quixotic.
• Although his plan was quixotic, he remained determined to achieve his goals.
• The environmental activist had a quixotic vision of a world without pollution.