stolid adj.

1560s, from French stolidite and directly from Late Latin stoliditatem (nominative stoliditas) "dullness, obtuseness, stupidity," from Latin stolidus (see stolid).

Proto-Indo-European root meaning "to put, stand, put in order," with derivatives referring to a standing object or place.

It forms all or part of: apostle; catastaltic; diastole; epistle; forestall; Gestalt; install; installment; pedestal; peristalsis; peristaltic; stale (adj.); stalk (n.); stall (n.1) "place in a stable for animals;" stall (n.2) "pretense to avoid doing something;" stall (v.1) "come to a stop, become stuck;" stallage; stallion; stele; stell; still (adj.); stilt; stole (n.); stolid; stolon; stout; stultify; systaltic; systole.

It is the hypothetical source of/evidence for its existence is provided by: Greek stellein "to put in order, make ready; equip or dress with weapons, clothes, etc.; prepare (for a journey), dispatch; to furl (sails);" Armenian stełc-anem "to prepare, create;" Albanian shtiell "to wind up, reel up, collect;" Old Church Slavonic po-steljo "I spread;" Old Prussian stallit "to stand;" Old English steall "standing place, stable," Old High German stellen "to set, place."

1766, "allege to be of unsound mind" (legal term), from Late Latin stultificare "turn into foolishness," from Latin stultus "foolish" (literally "uneducated, unmovable," from suffixed form of PIE root *stel- "to put, stand, put in order," with derivatives referring to a standing object or place) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put"). The first element is cognate with Latin stolidus "slow, dull, obtuse" (see stolid). Meaning "cause to appear foolish or absurd" is from 1809. Hence stultiloquy "foolish talk, silly babbling" (1650s). Related: Stultified; stultifying.