serious

adjective

• 1demanding or characterized by careful consideration or application:marriage is a serious matter we give serious consideration to safety recommendations
• solemn or thoughtful in character or manner:her face grew serious
• (of music, literature, or other art forms) requiring or meriting deep reflection:he bridges the gap between serious and popular music

• 2acting or speaking sincerely and in earnest, rather than in a joking or half-hearted manner:actors who are serious about their work

• 3significant or worrying because of possible danger or risk; not slight or negligible:she escaped serious injury

• 4 [attributive] informal substantial in terms of size, number, or quality:he suddenly had serious money to spend