- serious
- 1440, "expressing earnest purpose or thought" (of persons), from M.Fr. sérieux "grave, earnest" (14c.), from L.L. seriosus, from L. serius "weighty, important, grave," probably from a PIE base *swer- (cf. Lith. sveriu "to weigh, lift," svarus "heavy;" O.E. swære "heavy," Ger. schwer "heavy," Goth. swers "honored, esteemed," lit. "weighty"). As opposite of jesting, from 1712; as opposite of light (of music, theater, etc.), from 1762. Meaning "attended with danger" is from 1800. Phrase to take (something) seriously is attested from 1782.