Antonyms of adj serious-minded

1 sense of serious-minded

Sense 1
thoughtful, serious-minded -- (acting with or showing thought and good sense; "a sensible young man")

INDIRECT (VIA serious) -> frivolous -- (not serious in content or attitude or behavior; "a frivolous novel"; "a frivolous remark"; "a frivolous young woman")

Similarity of adj serious-minded

1 sense of serious-minded

Sense 1
thoughtful, serious-minded -- (acting with or showing thought and good sense; "a sensible young man")
       => serious (vs. frivolous) -- (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!")