真空(kong)(kong)，這一(yi)術語譯自拉丁文vacuo，其意義是(shi)虛(xu)無。其實(shi)真空(kong)(kong)應理解為(wei)(wei)氣體較稀薄的(de)空(kong)(kong)間。在指定的(de)空(kong)(kong)間內(nei)(nei)，低于一(yi)個大氣壓(ya)力的(de)氣體狀態統稱為(wei)(wei)真空(kong)(kong)。真空(kong)(kong)狀態下(xia)氣體稀薄程度(du)稱為(wei)(wei)真空(kong)(kong)度(du)（degreeofvacuum），通常用(yong)壓(ya)力值表示。因(yin)此(ci)真空(kong)(kong)包(bao)(bao)裝(zhuang)實(shi)際(ji)上不是(shi)完全(quan)真空(kong)(kong)的(de)，采用(yong)真空(kong)(kong)包(bao)(bao)裝(zhuang)技術包(bao)(bao)裝(zhuang)的(de)食(shi)品容器內(nei)(nei)的(de)真空(kong)(kong)度(du)通常在600-1333Pa。所以(yi)，又將真空(kong)(kong)包(bao)(bao)裝(zhuang)稱為(wei)(wei)減壓(ya)包(bao)(bao)裝(zhuang)或排氣包(bao)(bao)裝(zhuang)。