frivolous -
not serious in content or attitude or behavior; "a frivolous novel"; "a frivolous remark"; "a frivolous young woman"
serious requiring effort or concentration; complex and not easy to answer or solve; "raised serious objections to the proposal"; "the plan has a serious flaw"
superficial concerned with or comprehending only what is apparent or obvious; not deep or penetrating emotionally or intellectually; "superficial similarities"; "a superficial mind"; "his thinking was superficial and fuzzy"; "superficial knowledge"; "the superficial report didn't give the true picture"; "only superficial differences"