firmāmentum, i, n. [firmo], a strengthening, support, prop (class.; esp. freq. in the trop. sense and in Cic.).
I 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.—
B Transf., the sky fixed above the earth , the firmament (late Lat.), Tert. Bapt. 3; Aug. de Genes. ad lit. 2 et saep.—
II Trop.
A 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.—
B 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.