Lewis & Short

subscūs, ūdis, f. [sub-cudo], the tongue or tenon of a dovetail: subscudes appellantur cuneatae tabellae, quibus tabulae inter se configuntur, quia, quo eae immittuntur, succuditur, Fest. p. 306 Müll.: nec ulla subscus cohibet compagem alvei, Pac. ap. Fest. l. l. (Trag. Rel. v. 250 Rib.): terebratus multum sit et subscudes additae, Plaut. ib.; Cato, R. R. 18, 9; Vitr. 4, 7; 10, 6; 10, 10.
Plur.: subscudibus et catenis uncis retentari, Arn. 6, 16.
Collat. form of plur. subscudines, Aug. Civ. Dei, 15, 27.