obtuse (adj.)youdaoicibaDictYouDict[obtuse 词源字典]
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.[obtuse etymology, obtuse origin, 英语词源]
stolidity (n.)youdaoicibaDictYouDict
1560s, from Middle French stolidite and directly from Late Latin stoliditatem (nominative stoliditas) "dullness, obtuseness, stupidity," from Latin stolidus (see stolid).