Lewis & Short

sĭlex, ĭcis, m. (poet. and late Lat.; also fem., Verg. E. 1, 15; id. A. 6, 471; 6, 602; 8, 233; Ov. M. 9, 225; 9, 304; 9, 613; Amm. 14, 6, 16; cf. Quint. 1, 6, 2; gen. plur. silicum, Lucr. 6, 683; Luc. 4, 304) [root sar-, to be firm; cf.: solum, solidus].

  1. I. Any hard stone found in fields, a pebble-stone, a flint, flint-stone: silicem caedere, Cic. Div. 2, 41, 85: silice vias sternere, Liv. 41, 27; cf. id. 41, 27, § 7: silici scintillam excudere, Verg. A. 1, 174: gravem medios silicem jaculatus in hostes, Ov. M. 7, 139 et saep.: per ampla spatia urbis, subversasque silices, pavements, Amm. 14, 6, 16; cf.: silicem pedibus quae conteret atrum, Juv. 6, 350.
    Freq. joined with lapis: Ag. Illa mulier lapidem silicem subigere, ut se amet, potest. Mi. Pol id quidem haud mentire: nam tu es lapide silice stultior, Plaut. Poen. 1, 2, 77 sq.; Cato, R. R. 18, 3; Liv. 30, 43; Fest. s. v. lapidem, p. 115 Müll.; and in inscrr.: II VIRI VIAM LAPID(e) SILIC(e) STERN(endam) CVR(averunt), Inscr. Bull. dell’ Inst. 1839, p. 60; so Inscr. Orell. 6617.
    With saxum: porcum saxo silice percussit, Liv. 1, 24 fin.
    To denote hard-heartedness: non silice nati sumus, Cic. Tusc. 3, 6, 12: nec in tenero stat tibi corde silex, Tib. 1, 1, 64: nec rigidas silices in pectore gerit, Ov. M. 9, 614: et dicam silices pectus habere tuum, id. Tr. 3, 11, 4: moturaque duras Verba queror silices, id. M. 9, 304.
  2. II. In gen., a rock, crag (poet.), Lucr. 6, 683: validi silices, id. 1, 571; 2, 449: stabat acuta silex praecisis undique saxis, Verg. A. 8, 233: nudus silex, bare rick, Sen. Phoen. 69: excisae rupes durissimi silicis, Suet. Calig. 37: juventus duris silicum lassata metallis, Luc. 4, 304: Lycius Phrygiusque silex, Stat. S. 1, 2, 148.
    Of limestone, Ov. M. 7, 107; cf. Plin. 36, 23, 53, § 174.