obtuse (adj.)youdaoicibaDictYouDict
early 15c., "dull, blunted," from Middle French obtus (fem. obtuse), from Latin obtusus "blunted, dull," also used figuratively, past participle of obtundere "to beat against, make dull," from ob "against" (see ob-) + tundere "to beat," from PIE *(s)tud-e- "to beat, strike, push, thrust," from root *(s)teu- "to push, stick, knock, beat" (cognates: Latin tudes "hammer," Sanskrit tudati "he thrusts"). Sense of "stupid" is first found c. 1500. Related: Obtusely; obtuseness.
stolidity (n.)youdaoicibaDictYouDict
1560s, from Middle French stolidite and directly from Late Latin stoliditatem (nominative stoliditas) "dullness, obtuseness, stupidity," from Latin stolidus (see stolid).