Amussis
Amussis a level used by masons to test the evenness of a surface (Varr. ap. Non. 1.28 Festus, s. v.). But Sisenna (ap. Charis. 2, p. 178, Putsch.) defines it as a raddled surface used to prove whether work was perpendicular-tabula rubricata quae demittitur exominandi operis gratia, an rectum opus surgat. And Auson. (Idyll. 16.10) appears to denote by amussis a sort of norma, testing whether an angle made by two surfaces was a right angle. It appears from Vitruvius (1.6.6) that it was different from the regula (straight rule) and from the libella (plumb-line or square), and that it was used for obtaining a truer surface, whether horizontal or perpendicular, than those two instruments together would give. The amussis gives rise to the adverbs amussim, adamussim, examussim, also to amussitatus, in a metaphorical sense, meaning with perfect regularity and exactness (Varr. R. R. 2.1.26; Gel. 20.1.34; Plaut. Amph. 2.2, 213, Mil. 3.1, 38).
From William Smith (ed.), Dictionary of Greek and Roman Antiquities. Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities and Tufts University. Data accessed from https://github.com/PerseusDL/canonical-pdlrefwk/ on 17 October 2026.