Baretti: A dictionary of the English and Italian languages
Lástr-a, s. f. dim. Lástr-étta, Lástr-úccia, aug. Lástr-óne,
1. a stone, paving-stone, a flat broad stone, slate. Posar uno sulle lastre, to kill one upon the spot. Giacer sulle lastre, to be wounded. Mangiarsi le lastre, to act the bully or bravo; 2. any flat or level surface, table, board, plate, sheet of any metal.
Florio: a worlde of wordes, or most copious, dictionarie in Italian and English
lastra: as Lamína. Also a lath or broad splinter of wood. Also vsed for ballast for a ship. Also a flat slate stone or table.