真(zhen)空(kong)(kong)，這一(yi)(yi)術語譯自(zi)拉丁文vacuo，其意義(yi)是(shi)虛無。其實真(zhen)空(kong)(kong)應理解為(wei)氣體(ti)(ti)較(jiao)稀薄的空(kong)(kong)間。在指定的空(kong)(kong)間內(nei)，低于一(yi)(yi)個大氣壓(ya)力(li)的氣體(ti)(ti)狀(zhuang)態統稱(cheng)(cheng)為(wei)真(zhen)空(kong)(kong)。真(zhen)空(kong)(kong)狀(zhuang)態下氣體(ti)(ti)稀薄程度(du)稱(cheng)(cheng)為(wei)真(zhen)空(kong)(kong)度(du)（degreeofvacuum），通(tong)常用壓(ya)力(li)值表示。因此真(zhen)空(kong)(kong)包(bao)裝實際上不是(shi)完全真(zhen)空(kong)(kong)的，采用真(zhen)空(kong)(kong)包(bao)裝技術包(bao)裝的食品(pin)容(rong)器內(nei)的真(zhen)空(kong)(kong)度(du)通(tong)常在600-1333Pa。所以，又將(jiang)真(zhen)空(kong)(kong)包(bao)裝稱(cheng)(cheng)為(wei)減壓(ya)包(bao)裝或排氣包(bao)裝。