flippant Antonyms

serious according to the book sober solemn somber stereotyped thoughtful time-honored trad sincere shared severe set rife reverent respectful reactionary proverbial mutual vested weighty archconservative bog-standard bien pensant by the numbers old-line po-faced time-honoured traditionalistic standpat buttoned-down widespread wonted recognised authorised canonical ultraconservative brassbound button-down meditative inveterate average benevolent broad broody caring careful cautious circumspect authorized