真空(kong)(kong)，這一(yi)術語譯自拉丁文(wen)vacuo，其意義(yi)是虛無。其實(shi)真空(kong)(kong)應(ying)理解為氣體較稀(xi)薄(bo)的空(kong)(kong)間。在(zai)指定的空(kong)(kong)間內(nei)，低(di)于一(yi)個大氣壓(ya)力的氣體狀(zhuang)態統稱為真空(kong)(kong)。真空(kong)(kong)狀(zhuang)態下氣體稀(xi)薄(bo)程度(du)稱為真空(kong)(kong)度(du)（degreeofvacuum），通常(chang)用壓(ya)力值表示(shi)。因此真空(kong)(kong)包(bao)裝實(shi)際上不是完全真空(kong)(kong)的，采用真空(kong)(kong)包(bao)裝技術包(bao)裝的食(shi)品(pin)容器(qi)內(nei)的真空(kong)(kong)度(du)通常(chang)在(zai)600-1333Pa。所以，又將(jiang)真空(kong)(kong)包(bao)裝稱為減壓(ya)包(bao)裝或排氣包(bao)裝。