真(zhen)空(kong)(kong)，這一術語譯(yi)自拉丁文(wen)vacuo，其意(yi)義是(shi)虛無。其實真(zhen)空(kong)(kong)應理(li)解為氣(qi)(qi)體(ti)較稀薄的(de)(de)空(kong)(kong)間。在指定的(de)(de)空(kong)(kong)間內(nei)，低于一個大(da)氣(qi)(qi)壓(ya)(ya)力的(de)(de)氣(qi)(qi)體(ti)狀態統稱為真(zhen)空(kong)(kong)。真(zhen)空(kong)(kong)狀態下氣(qi)(qi)體(ti)稀薄程度(du)稱為真(zhen)空(kong)(kong)度(du)（degreeofvacuum），通(tong)常用壓(ya)(ya)力值表(biao)示。因此真(zhen)空(kong)(kong)包裝(zhuang)實際上不(bu)是(shi)完(wan)全真(zhen)空(kong)(kong)的(de)(de)，采(cai)用真(zhen)空(kong)(kong)包裝(zhuang)技(ji)術包裝(zhuang)的(de)(de)食品容(rong)器內(nei)的(de)(de)真(zhen)空(kong)(kong)度(du)通(tong)常在600-1333Pa。所以，又將真(zhen)空(kong)(kong)包裝(zhuang)稱為減壓(ya)(ya)包裝(zhuang)或(huo)排氣(qi)(qi)包裝(zhuang)。