stolid (adj.)youdaoicibaDictYouDict[stolid 词源字典]
c. 1600, back-formation from stolidity, or else from Middle French stolide (16c.), from Latin stolidus "insensible, dull, slow, brutish, rude, stupid," properly "unmovable," related to stultus "foolish," from PIE root *stel- "to put, stand" (see stall (n.1)).[stolid etymology, stolid origin, 英语词源]