真(zhen)空(kong)(kong)，這(zhe)一(yi)術語譯自拉丁文vacuo，其(qi)意義是虛(xu)無。其(qi)實真(zhen)空(kong)(kong)應理(li)解為(wei)(wei)氣(qi)(qi)體(ti)較稀薄(bo)的(de)空(kong)(kong)間。在指定(ding)的(de)空(kong)(kong)間內，低于一(yi)個大(da)氣(qi)(qi)壓(ya)力(li)的(de)氣(qi)(qi)體(ti)狀態統稱(cheng)為(wei)(wei)真(zhen)空(kong)(kong)。真(zhen)空(kong)(kong)狀態下氣(qi)(qi)體(ti)稀薄(bo)程(cheng)度稱(cheng)為(wei)(wei)真(zhen)空(kong)(kong)度（degreeofvacuum），通常(chang)用壓(ya)力(li)值表(biao)示。因此(ci)真(zhen)空(kong)(kong)包(bao)(bao)裝實際上不是完全(quan)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)食品容器(qi)內的(de)真(zhen)空(kong)(kong)度通常(chang)在600-1333Pa。所以，又將真(zhen)空(kong)(kong)包(bao)(bao)裝稱(cheng)為(wei)(wei)減壓(ya)包(bao)(bao)裝或排氣(qi)(qi)包(bao)(bao)裝。