Capricious (adjective)

1. Likely to change one's mind impulsively; unpredictable.
2. Governed by or subject to caprice; determined by chance or impulse rather than by necessity, reason, or principle.

Origin:

From latin capriciōsus, from caper ("he-goat") + -ōsus ("full of"), so called because the he-goat was thought to change its mind frequently.

Examples:

1. He was a capricious ruler, who changed his mind frequently and without warning.
2. The weather in the mountains is notoriously capricious, changing suddenly and without warning.
3. She was known for her capricious nature, often changing her mind at the last minute.
4. The stock market can be capricious, with prices fluctuating wildly on a whim.
5. The artist's work was criticized for being too capricious, lacking a clear direction or purpose.