The adjective capricious means often or sudden desire for change of mood, behavior or idea.
Synonyms are inconstant, inconsistent, impulsive or unpredictable.
The word origins from French (16th century) capricieux meaning “whimsical” and Italian capriccioso which is borrowed from capriccio.
He is known for having a capricious decision making.
I got allergies because of the capricious weather.
Fiona says that women are more capricious than men.