真(zhen)(zhen)空(kong)(kong)，這(zhe)一術語譯自(zi)拉丁文(wen)vacuo，其意義是虛無。其實真(zhen)(zhen)空(kong)(kong)應理解(jie)為(wei)(wei)(wei)氣體較稀薄的(de)(de)空(kong)(kong)間。在指定的(de)(de)空(kong)(kong)間內，低于一個大氣壓力的(de)(de)氣體狀(zhuang)態(tai)統稱為(wei)(wei)(wei)真(zhen)(zhen)空(kong)(kong)。真(zhen)(zhen)空(kong)(kong)狀(zhuang)態(tai)下氣體稀薄程度稱為(wei)(wei)(wei)真(zhen)(zhen)空(kong)(kong)度（degreeofvacuum），通常(chang)用(yong)壓力值(zhi)表示。因此(ci)真(zhen)(zhen)空(kong)(kong)包(bao)(bao)(bao)裝實際上不是完全真(zhen)(zhen)空(kong)(kong)的(de)(de)，采用(yong)真(zhen)(zhen)空(kong)(kong)包(bao)(bao)(bao)裝技術包(bao)(bao)(bao)裝的(de)(de)食品容器內的(de)(de)真(zhen)(zhen)空(kong)(kong)度通常(chang)在600-1333Pa。所以，又(you)將(jiang)真(zhen)(zhen)空(kong)(kong)包(bao)(bao)(bao)裝稱為(wei)(wei)(wei)減壓包(bao)(bao)(bao)裝或排氣包(bao)(bao)(bao)裝。