frivolous Antonyms

serious staid ruling rememberable reigning regnant ranking quintessential protrusile prominent sacred salient sedate solemn sober significant signal shrewd sensible seminal seismic prognathous principal pertinent peopled parlous parenchyma paramount overruling overriding over outstanding pivotal populated primary primal pressing prerequisite preponderant prepollent premier predominant portentous obligatory world-shaking major league big league superordinate major key climactic