disapproval If you say that someone is flighty, you disapprove of them because they are not very serious or reliable and keep changing from one activity, idea, or partner to another. Isabelle was a frivolous little fool, vain and flighty. a woman who is flighty changes her ideas and opinions often, and only remains interested in people or things for a short time
given to disordered fancies and extravagant conduct; volatile; giddy; eccentric; slighty delirious
the trait of acting unpredictably and more from whim or caprice than from reason or judgment; "I despair at the flightiness and whimsicality of my memory