真空(kong)(kong)(kong)，這一術語譯自(zi)拉丁文vacuo，其(qi)意義是(shi)(shi)虛無。其(qi)實(shi)真空(kong)(kong)(kong)應理(li)解為(wei)氣體(ti)較(jiao)稀薄(bo)的(de)(de)空(kong)(kong)(kong)間(jian)。在(zai)指定的(de)(de)空(kong)(kong)(kong)間(jian)內(nei)(nei)，低于(yu)一個(ge)大(da)氣壓力的(de)(de)氣體(ti)狀態統(tong)稱為(wei)真空(kong)(kong)(kong)。真空(kong)(kong)(kong)狀態下氣體(ti)稀薄(bo)程(cheng)度稱為(wei)真空(kong)(kong)(kong)度（degreeofvacuum），通(tong)常(chang)(chang)用(yong)(yong)壓力值(zhi)表(biao)示。因(yin)此真空(kong)(kong)(kong)包(bao)(bao)裝實(shi)際上不是(shi)(shi)完(wan)全(quan)真空(kong)(kong)(kong)的(de)(de)，采用(yong)(yong)真空(kong)(kong)(kong)包(bao)(bao)裝技術包(bao)(bao)裝的(de)(de)食(shi)品(pin)容器內(nei)(nei)的(de)(de)真空(kong)(kong)(kong)度通(tong)常(chang)(chang)在(zai)600-1333Pa。所以，又將真空(kong)(kong)(kong)包(bao)(bao)裝稱為(wei)減壓包(bao)(bao)裝或排氣包(bao)(bao)裝。