真空(kong)(kong)，這一術(shu)語譯自(zi)拉丁文(wen)vacuo，其(qi)意義是(shi)虛無。其(qi)實真空(kong)(kong)應理解為(wei)氣體(ti)較稀(xi)薄的空(kong)(kong)間(jian)(jian)。在指定的空(kong)(kong)間(jian)(jian)內(nei)，低于(yu)一個大氣壓(ya)(ya)力的氣體(ti)狀(zhuang)態統稱為(wei)真空(kong)(kong)。真空(kong)(kong)狀(zhuang)態下氣體(ti)稀(xi)薄程(cheng)度(du)稱為(wei)真空(kong)(kong)度(du)（degreeofvacuum），通常(chang)用壓(ya)(ya)力值表示。因此真空(kong)(kong)包(bao)裝(zhuang)(zhuang)實際上不是(shi)完全真空(kong)(kong)的，采用真空(kong)(kong)包(bao)裝(zhuang)(zhuang)技術(shu)包(bao)裝(zhuang)(zhuang)的食品容(rong)器內(nei)的真空(kong)(kong)度(du)通常(chang)在600-1333Pa。所(suo)以，又將真空(kong)(kong)包(bao)裝(zhuang)(zhuang)稱為(wei)減壓(ya)(ya)包(bao)裝(zhuang)(zhuang)或排氣包(bao)裝(zhuang)(zhuang)。