obtuseyoudaoicibaDictYouDict[obtuse 词源字典]
obtuse: [16] The etymological meaning of obtuse is ‘beaten down, blunted’. It comes from Latin obtūsus, the past participle of obtundere, a compound verb formed from the prefix ob- ‘against’ and tundere ‘beat’ (source of English contusion and related to toil). The notion of being ‘dulled’ or ‘blunted’ led to its being used for ‘having dulled wits, stupid’, and the idea of bluntness also lies behind its geometrical use for an angle of more than 90 degrees (as contrasted with the ‘sharp’ acute angle).
=> contusion, toil[obtuse etymology, obtuse origin, 英语词源]
acutangularyoudaoicibaDictYouDict
"Having or forming one or more acute angles; acute-angled", Mid 17th cent.; earliest use found in John Collins (1625–1683), mathematician and scientific administrator. From post-classical Latin acutangulus + -ar.