Adjective
unserious (comparative more unserious, superlative most unserious)
Not serious; characterized by a lack of seriousness (of attitude, approach, style etc.).
Synonyms: facetious, flippant, frivolous
There are a lot of people who know me who can't understand for the life of them why I would got to work on something as unserious as baseball. If they only knew. A. Bartlett Giamatti
The phrase 'misuse of privilege' is becoming a free pass to tear apart pretty much anybody we choose to. It's becoming a devalued term, and it's making us lose our capacity for empathy and for distinguishing between serious and unserious transgressions. Jon Ronson
The best way to make the most serious point in the world is to be as unserious as possible. Mika
People in the comments mostly laughed at the serious, yet unserious vlog. Source: Internet
Because one of these profoundly unserious people is the president of the United States who was in a position to, and did, order US troops to invade, conquer, and occupy Iraq. Source: Internet
"I can tell from the content and how it's presented, since I'd assume that 'fake news' is rather unscientific and unserious," Kaup said. Source: Internet