instratum
From LSJ
προγράψαντες οὖν τά τε θεωρήματα καὶ τὰ ἐπιτάγματα τὰ χρεῖαν ἔχοντα εἰς τὰς ἀποδείξιας αὐτῶν μετὰ ταῦτα γραψοῦμές τοι τὰ προκείμενα → having therefore written at the beginning the theorems and the postulates that are necessary for their proofs, we will then write out for you the propositions
instrātum: i, n. insterno,
I a covering (ante- and post-class.), Cato, R. R. 10, 3; Dig. 50, 16, 45.
īnstrātum, ī, n., s. īn-sternono. I.