Lewis & Short

rĕ-tundo, tŭdi (also rettŭdi, Phaedr. 4, 22, 21 Orell. N. cr.), tūsum (retunsus, Plaut. Ps. 1, 2, 27; 4, 4, 8), 3, v. a., to beat or pound back any thing sharp, i. e. to blunt, dull (class.).

  1. I. Lit.: ferrum, Cic. Sull. 30, 83: in Massagetas ferrum, Hor. C. 1, 35, 39: gladios in rem publicam destrictos, Cic. Cat. 3, 1, 2: ascias (tilia), Plin. 16, 40, 76, § 207: hamata tela, Ov. Am. 2, 9, 13; cf.: conjurationis nefaria tela, Cic. Dom. 24, 63.
  2. II. Trop., to blunt, dull, deaden, weaken, restrain, check, etc.: (censorii stili) mucronem, Cic. Clu. 44, 123: mucronem ingenii cotidianā pugnā, Quint. 10, 5, 16 (with deteratur fulgor): belle iste puer retundit Antonium, Atticus ap. Cic. Att. 16, 15, 3: collegam, Tac. A. 5, 11: animum, qui luxuriā et lasciviā Diffluit, check, repress, Ter. Heaut. 5, 1, 73; so, impetum erumpentium, Liv. 2, 33: sermones, Cael. ap. Cic. Fam. 8, 6, 1; cf.: Aetolorum linguas, Liv. 33, 31: improbitatem, Lentul. ap. Cic. Fam. 12, 14, 3; Quint. 6, 4, 11 (with propulsare eos): superbiam, Phaedr. 4, 22, 21: iram, Prud. Cath. 6, 94; cf.: Boreas retundit pelagus (ira motum), Luc. 5, 601 Cort. N. cr.
    Hence, rĕ-tūsus (retunsus, v. supra), a, um, P. a., blunted, blunt, dull.
    1. A. Lit.: securis, Plaut. Ps. 1, 2, 27: ferrum, Verg. G. 2, 301: tela, Ov. M. 12, 496: retusum et crassum ferramentum, Col. 4, 24, 21: aurum hebeti mucrone, Lucr. 5, 1274.
    2. B. Trop.: mihi cor retunsum’st oppugnando pectore, deprived of feeling, Plaut. Ps. 4, 4, 8: cor, Claud. Eutr. 2, 47: ingenia (opp. acuta), Cic. Div. 1, 36, 79 fin.: stella crine retuso, weakened, dimmed, Claud. IV. Cons. Hon. 185; cf. comp.: acumen retusius, Hier. Ep. 69, 4: fervor belli, subdued, Sil. 8, 321: res, impaired, unfortunate, id. 16, 21.