(with) a sound of bells

fickle, irresponsible

not clear or bright; slow to understand; not exciting or interesting

unintelligent

not serious or important; enjoying pleasure (too much)

trivial, silly

causing, having, the feeling that everything is turning round so that one cannot stand steady

silly, impulsive

(especially) (doing things, done) without a proper sense of responsibility

careless, reckless

behaving as if a little mad

giddy