Crustum, crusti, neut. gen. Virg.A crust of breade or of meate costed.Distringe liuius panis crustum.Chippe this breade.Crústulum li, n cor. Dimiuumum. Hor. A wafer or like thinne cake o be giuen to children.Crustula lambere. Iuuenal.
Lewis and Short: Latin dictionary
crustum, i, n. [access. form to crusta], pastry, any thing baked, Hor. Ep. 1, 1, 78; Verg. A. 7, 115; Inscr. Grut. 173, 4; 373, 8.