quarto /'kwxtau; 'kworto/ n (pl ~s) /-tauz; -tor/ (also written 亦書(shū)作 4to) size given by folding a sheet of paper twice (making four leaves or eight pages); book made of sheets so folded (usu about 9 by 12 in) : 四開(kāi) (將一張紙折兩次，折成四張八頁(yè)); 四開(kāi)本的書(shū) (通常為 9x12 吋)： the first ~ of 'Hamlet'. 哈蝸雷特的第一四開(kāi)本。