/ fəˈsiːʃəs; NAmE / adjective
trying to appear amusing and intelligent at a time when other people do not think it is appropriate, and when it would be better to be serious
SYN flippant :
a facetious comment / remark
Stop being facetious; this is serious.
► fa·cetious·ly adverb
► fa·cetious·ness noun [ U ]
••
WORD ORIGIN
late 16th cent. (in the general sense witty, amusing ): from French facétieux , from facétie , from Latin facetia jest, from facetus witty.