Adjective serious has 6 senses
- serious - 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!"
Antonyms: frivolous, airheaded, dizzy, empty-headed, featherbrained, giddy, light-headed, lightheaded, silly, flighty, flyaway, flippant, light-minded, idle, light, trivial
- serious - of great consequence; "marriage is a serious matter"
Antonym: unimportant (indirect, via important)
- dangerous, grave, grievous, serious, severe, life-threatening - causing fear or anxiety by threatening great harm; "a dangerous operation"; "a grave situation"; "a grave illness"; "grievous bodily harm"; "a serious wound"; "a serious turn of events"; "a severe case of pneumonia"; "a life-threatening disease"
Antonyms: noncritical, noncrucial (indirect, via critical)
- good, serious - appealing to the mind; "good music"; "a serious book"
Antonym: nonintellectual (indirect, via intellectual)
- unplayful, serious, sober - completely lacking in playfulness
- 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"
Antonym: easy (indirect, via difficult)
,