真(zhen)(zhen)空(kong)(kong)(kong)，這一術語(yu)譯自拉(la)丁文(wen)vacuo，其(qi)意義是虛無。其(qi)實真(zhen)(zhen)空(kong)(kong)(kong)應理解為(wei)氣(qi)體較(jiao)稀薄的(de)(de)空(kong)(kong)(kong)間。在指定的(de)(de)空(kong)(kong)(kong)間內(nei)，低(di)于一個大氣(qi)壓力的(de)(de)氣(qi)體狀態統稱為(wei)真(zhen)(zhen)空(kong)(kong)(kong)。真(zhen)(zhen)空(kong)(kong)(kong)狀態下氣(qi)體稀薄程度(du)稱為(wei)真(zhen)(zhen)空(kong)(kong)(kong)度(du)（degreeofvacuum），通常(chang)用(yong)壓力值表示。因此(ci)真(zhen)(zhen)空(kong)(kong)(kong)包(bao)(bao)(bao)(bao)裝實際上不是完(wan)全真(zhen)(zhen)空(kong)(kong)(kong)的(de)(de)，采用(yong)真(zhen)(zhen)空(kong)(kong)(kong)包(bao)(bao)(bao)(bao)裝技術包(bao)(bao)(bao)(bao)裝的(de)(de)食品(pin)容器內(nei)的(de)(de)真(zhen)(zhen)空(kong)(kong)(kong)度(du)通常(chang)在600-1333Pa。所以，又將真(zhen)(zhen)空(kong)(kong)(kong)包(bao)(bao)(bao)(bao)裝稱為(wei)減壓包(bao)(bao)(bao)(bao)裝或排氣(qi)包(bao)(bao)(bao)(bao)裝。