真空(kong)(kong)，這一(yi)術語譯自拉(la)丁文vacuo，其意(yi)義是虛無。其實(shi)真空(kong)(kong)應理解為(wei)(wei)氣(qi)(qi)體較(jiao)稀薄的(de)(de)空(kong)(kong)間。在(zai)指定的(de)(de)空(kong)(kong)間內，低于一(yi)個大氣(qi)(qi)壓(ya)力的(de)(de)氣(qi)(qi)體狀態統稱(cheng)為(wei)(wei)真空(kong)(kong)。真空(kong)(kong)狀態下氣(qi)(qi)體稀薄程度稱(cheng)為(wei)(wei)真空(kong)(kong)度（degreeofvacuum），通(tong)常(chang)用壓(ya)力值表示。因此真空(kong)(kong)包(bao)(bao)裝(zhuang)實(shi)際上不是完全(quan)真空(kong)(kong)的(de)(de)，采用真空(kong)(kong)包(bao)(bao)裝(zhuang)技術包(bao)(bao)裝(zhuang)的(de)(de)食品(pin)容器內的(de)(de)真空(kong)(kong)度通(tong)常(chang)在(zai)600-1333Pa。所以，又將真空(kong)(kong)包(bao)(bao)裝(zhuang)稱(cheng)為(wei)(wei)減壓(ya)包(bao)(bao)裝(zhuang)或排(pai)氣(qi)(qi)包(bao)(bao)裝(zhuang)。