not serious or sensible
frivolous - silly
Something ‘frivolous’ is silly and of little weight or importance. You can use the word in relation to anything that you do not consider to be worthwhile or serious in both a social and professional context. The term can also be used to refer to a person who behaves in an overly light-hearted way and often fails to take things as seriously as they should. Expresses disapproval.
It can be hard to run a business in a litigious society because you will likely face a number of frivolous lawsuits.
I didn’t like the frivolousness of our new marketing campaign. It just seemed a little kitsch and tacky to me.
My attempts at frivolity did not go down well in the business meeting. I probably should have been more professional.