真空(kong)(kong)，這一(yi)術語(yu)譯自拉丁文vacuo，其意義是虛無。其實(shi)真空(kong)(kong)應理解為氣(qi)(qi)體(ti)較稀(xi)薄的(de)空(kong)(kong)間。在指(zhi)定的(de)空(kong)(kong)間內，低于一(yi)個大氣(qi)(qi)壓力的(de)氣(qi)(qi)體(ti)狀態統稱(cheng)(cheng)為真空(kong)(kong)。真空(kong)(kong)狀態下氣(qi)(qi)體(ti)稀(xi)薄程(cheng)度(du)稱(cheng)(cheng)為真空(kong)(kong)度(du)（degreeofvacuum），通常(chang)(chang)用壓力值表示。因此真空(kong)(kong)包(bao)裝實(shi)際(ji)上(shang)不(bu)是完(wan)全真空(kong)(kong)的(de)，采用真空(kong)(kong)包(bao)裝技術包(bao)裝的(de)食品容器內的(de)真空(kong)(kong)度(du)通常(chang)(chang)在600-1333Pa。所(suo)以(yi)，又將真空(kong)(kong)包(bao)裝稱(cheng)(cheng)為減壓包(bao)裝或排(pai)氣(qi)(qi)包(bao)裝。