crotalum
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
crŏtălum: i, n., = κρόταλον>,
I a rattle, a bell, castanet, used to accompany wanton dances, P. Scip. ap. Macr. S. 2, 10; Cic. Pis. 9, 20 al.
