na-adjective, noun
frivolous; fickle; insincere; capricious; cold-hearted
Describes a person or attitude that is shallow, changeable, and lacking sincerity or depth. Often used in literary or critical contexts. The noun form can refer to such a quality or a capricious act.
彼の浮薄な態度に周囲は呆れていた。
People around him were disgusted by his frivolous attitude.
浮薄な人間関係は長続きしない。
Shallow, insincere relationships don't last long.
Compound of 浮 (fu, 'floating, transient') and 薄 (haku, 'thin, shallow'). The combination suggests a light, unsteady, and superficial nature.