← BackshareGuessunfrivolous/ʌnˈfrɪvələs/adjectiveSerious, sensible, and not silly or trivial.His unfrivolous remarks helped the group stay on task.The meeting had an unfrivolous tone, focusing only on the budget cuts.She chose an unfrivolous outfit for the job interview, a plain black suit.SynonymsserioussoberearnestAntonymsfrivolous