stolid (adj.) Look up stolid at Dictionary.com
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)).