cryptoporticus
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
cryptŏportĭcus: ūs, f. vox hibrida, from κρυπτός> and porticus,
I a covered gallery or passage, a vault, a hall, Plin. Ep. 2, 17, 16 sq.; 5, 6, 27 sq. al.
