真(zhen)(zhen)空(kong)(kong)(kong)，這(zhe)一術語(yu)譯自拉丁文vacuo，其(qi)意義是虛無。其(qi)實(shi)真(zhen)(zhen)空(kong)(kong)(kong)應理解為(wei)氣(qi)體(ti)較(jiao)稀(xi)薄的(de)空(kong)(kong)(kong)間。在(zai)指(zhi)定(ding)的(de)空(kong)(kong)(kong)間內，低(di)于一個大(da)氣(qi)壓力的(de)氣(qi)體(ti)狀態統(tong)稱為(wei)真(zhen)(zhen)空(kong)(kong)(kong)。真(zhen)(zhen)空(kong)(kong)(kong)狀態下氣(qi)體(ti)稀(xi)薄程度(du)稱為(wei)真(zhen)(zhen)空(kong)(kong)(kong)度(du)（degreeofvacuum），通(tong)常用(yong)(yong)壓力值表示。因此真(zhen)(zhen)空(kong)(kong)(kong)包裝(zhuang)實(shi)際(ji)上不是完(wan)全(quan)真(zhen)(zhen)空(kong)(kong)(kong)的(de)，采(cai)用(yong)(yong)真(zhen)(zhen)空(kong)(kong)(kong)包裝(zhuang)技(ji)術包裝(zhuang)的(de)食品容(rong)器內的(de)真(zhen)(zhen)空(kong)(kong)(kong)度(du)通(tong)常在(zai)600-1333Pa。所以，又將(jiang)真(zhen)(zhen)空(kong)(kong)(kong)包裝(zhuang)稱為(wei)減壓包裝(zhuang)或排氣(qi)包裝(zhuang)。