真(zhen)(zhen)空(kong)(kong)，這(zhe)一術語譯自拉丁文vacuo，其意義是虛無。其實真(zhen)(zhen)空(kong)(kong)應理解(jie)為氣(qi)體(ti)(ti)較稀(xi)薄的(de)(de)空(kong)(kong)間。在指定的(de)(de)空(kong)(kong)間內(nei)，低于(yu)一個大氣(qi)壓力的(de)(de)氣(qi)體(ti)(ti)狀態(tai)統(tong)稱(cheng)為真(zhen)(zhen)空(kong)(kong)。真(zhen)(zhen)空(kong)(kong)狀態(tai)下氣(qi)體(ti)(ti)稀(xi)薄程度(du)(du)稱(cheng)為真(zhen)(zhen)空(kong)(kong)度(du)(du)（degreeofvacuum），通(tong)常用(yong)壓力值表示。因(yin)此真(zhen)(zhen)空(kong)(kong)包裝實際(ji)上不是完全真(zhen)(zhen)空(kong)(kong)的(de)(de)，采用(yong)真(zhen)(zhen)空(kong)(kong)包裝技術包裝的(de)(de)食品容器內(nei)的(de)(de)真(zhen)(zhen)空(kong)(kong)度(du)(du)通(tong)常在600-1333Pa。所以，又將真(zhen)(zhen)空(kong)(kong)包裝稱(cheng)為減壓包裝或排氣(qi)包裝。