firmāmentum, i, n. id., a strengthening, support, prop (class.; esp. freq. in the trop. sense and in Cic.). Lit.: transversaria tigna iniciuntur, quae firmamento esse possint, Caes. B. C. 2, 15, 2: ossa nervique et articuli, firmamenta totius corporis, Sen. de Ira, 2, 1, 2: vincula et firmamenta membrorum, Gell. 13, 22, 9.— Transf., the sky fixed above the earth, the firmament (late Lat.), Tert. Bapt. 3; Aug. de Genes. ad lit. 2 et saep.— Trop. In gen., a support, prop, stay: eum ordinem, qui exercet vectigalia, firmamentum ceterorum ordinum recte esse dicemus, Cic. de Imp. Pomp. 7, 17: firmamentum ac robur totius accusationis, id. Mur. 28, 58; cf.: multo plus firmamenti ac roboris, id. de Imp. Pomp. 4, 10: parum firmamenti et parum virium, id. Clu. 2, 5: rei publicae, id. Planc. 9, 23; cf.: imperii populi Romani, id. Phil. 3, 5, 13: stabilitatis constantiaeque fides est, id. Lael. 18, 65: dignitatis, id. Tusc. 4, 3, 7: honor sacerdotii firmamentum, potentiae adsumebatur, Tac. H. 5, 8: si ullum firmamentum in illo teste posuisses, Cic. Fl. 37, 92: legionem ex subsidiis in primam aciem firmamentum ducit, as a support, Liv. 29, 2, 9.—In plur.: Romulus cum haec egregia duo firmamenta rei publicae peperisset, auspicia et senatum, Cic. Rep. 2, 10.— In partic., rhet. t. t., the chief support of an argument, the main point, τὸ συνέχον, Cic. Inv. 1, 14, 19; id. Part. 29, 103; Auct. Her. 1, 16, 26; Quint. 3, 11, 1; 9; 12 sq.