真(zhen)空(kong)(kong)，這一術語譯自拉丁文vacuo，其意義是虛無。其實真(zhen)空(kong)(kong)應理(li)解為氣(qi)(qi)體(ti)(ti)較(jiao)稀薄的(de)空(kong)(kong)間。在指(zhi)定的(de)空(kong)(kong)間內，低于一個(ge)大氣(qi)(qi)壓力(li)的(de)氣(qi)(qi)體(ti)(ti)狀態統(tong)稱為真(zhen)空(kong)(kong)。真(zhen)空(kong)(kong)狀態下氣(qi)(qi)體(ti)(ti)稀薄程度(du)(du)稱為真(zhen)空(kong)(kong)度(du)(du)（degreeofvacuum），通常(chang)用壓力(li)值表(biao)示(shi)。因(yin)此真(zhen)空(kong)(kong)包(bao)(bao)裝實際上不(bu)是完全真(zhen)空(kong)(kong)的(de)，采用真(zhen)空(kong)(kong)包(bao)(bao)裝技術包(bao)(bao)裝的(de)食(shi)品容器內的(de)真(zhen)空(kong)(kong)度(du)(du)通常(chang)在600-1333Pa。所以，又將真(zhen)空(kong)(kong)包(bao)(bao)裝稱為減(jian)壓包(bao)(bao)裝或(huo)排氣(qi)(qi)包(bao)(bao)裝。