Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
scū̆tra, ae, f., a flat tray, dish, or platter of a nearly square form, Cato, R. R. 157, 11; Plaut. Pers. 1, 3, 8; Vulg. 3 Reg. 7, 40; 7, 45.
Collat. form scūta, ae, Lucil. ap. Prisc. p. 618 P