being or characterized by concepts or their formation; "conceptual discussions"; "the schizophrenic loses ability to abstract or do conceptual thinking"; "sex is a notional category, gender is a grammatical category"
requiring effort or concentration; complex and not easy to answer or solve; "raised serious objections to the proposal"; "the plan has a serious flaw"
of great consequence; "marriage is a serious matter"
concerned with work or important matters rather than play or trivialities; "a serious student of history"; "a serious attempt to learn to ski"; "gave me a serious look"; "a serious young man"; "are you serious or joking?"; "Don't be so serious!"