Quixotic (adjective)

Foolishly impractical, especially in the pursuit of ideals; marked by rash, lofty, or extravagant ideas or aims.

Origin:

From spanish quixote "don quixote" (17th century novel by miguel de cervantes).

Examples:

1. He"s a bit quixotic, he"s always dreaming up grand plans that never come to fruition.
2. His quixotic ideas about saving the world were admirable, but unrealistic.
3. She was too quixotic, her plans were impossible to execute and too costly.
4. His quixotic approach to solving problems led to a lot of wasted time and resources.
5. He had a quixotic vision of a utopia that was impossible to achieve.