真空(kong)(kong)(kong)(kong)，這一(yi)術語譯自拉丁文vacuo，其(qi)意義是(shi)虛無。其(qi)實真空(kong)(kong)(kong)(kong)應理解為氣(qi)(qi)體較稀(xi)薄的(de)(de)空(kong)(kong)(kong)(kong)間。在指定的(de)(de)空(kong)(kong)(kong)(kong)間內，低于一(yi)個(ge)大(da)氣(qi)(qi)壓力的(de)(de)氣(qi)(qi)體狀(zhuang)態統稱為真空(kong)(kong)(kong)(kong)。真空(kong)(kong)(kong)(kong)狀(zhuang)態下氣(qi)(qi)體稀(xi)薄程度(du)稱為真空(kong)(kong)(kong)(kong)度(du)（degreeofvacuum），通(tong)常(chang)用壓力值表示。因(yin)此真空(kong)(kong)(kong)(kong)包(bao)裝實際上不是(shi)完全真空(kong)(kong)(kong)(kong)的(de)(de)，采用真空(kong)(kong)(kong)(kong)包(bao)裝技(ji)術包(bao)裝的(de)(de)食品(pin)容(rong)器內的(de)(de)真空(kong)(kong)(kong)(kong)度(du)通(tong)常(chang)在600-1333Pa。所(suo)以，又將真空(kong)(kong)(kong)(kong)包(bao)裝稱為減壓包(bao)裝或(huo)排氣(qi)(qi)包(bao)裝。