真空(kong)(kong)(kong)，這一術語譯自拉丁文vacuo，其意義(yi)是虛(xu)無(wu)。其實(shi)真空(kong)(kong)(kong)應(ying)理(li)解(jie)為(wei)(wei)氣(qi)體較(jiao)稀(xi)薄的(de)(de)空(kong)(kong)(kong)間。在指(zhi)定的(de)(de)空(kong)(kong)(kong)間內，低于一個大氣(qi)壓力的(de)(de)氣(qi)體狀態統(tong)稱為(wei)(wei)真空(kong)(kong)(kong)。真空(kong)(kong)(kong)狀態下氣(qi)體稀(xi)薄程度稱為(wei)(wei)真空(kong)(kong)(kong)度（degreeofvacuum），通常(chang)用壓力值表(biao)示。因此真空(kong)(kong)(kong)包裝(zhuang)實(shi)際(ji)上不是完全真空(kong)(kong)(kong)的(de)(de)，采用真空(kong)(kong)(kong)包裝(zhuang)技術包裝(zhuang)的(de)(de)食品容器內的(de)(de)真空(kong)(kong)(kong)度通常(chang)在600-1333Pa。所(suo)以，又將真空(kong)(kong)(kong)包裝(zhuang)稱為(wei)(wei)減壓包裝(zhuang)或排氣(qi)包裝(zhuang)。