Don't hire him for this project; he's a frivol who never takes responsibility seriously.

Her notebook was filled with frivols, small, half-formed ideas and sketches she never intended to pursue.

She set aside her frivolities to focus on the charity project that needed real attention.

Despite his serious responsibilities, he was often dismissed as a frivoler by his colleagues.

Her constant frivolousity during meetings frustrated her colleagues, who preferred a more serious approach.