真空(kong)(kong)，這一(yi)術語譯(yi)自拉丁(ding)文vacuo，其意義是虛無。其實真空(kong)(kong)應理解(jie)為(wei)氣(qi)體(ti)較稀薄的空(kong)(kong)間(jian)。在(zai)指定(ding)的空(kong)(kong)間(jian)內，低于(yu)一(yi)個大(da)氣(qi)壓力的氣(qi)體(ti)狀態(tai)統稱(cheng)為(wei)真空(kong)(kong)。真空(kong)(kong)狀態(tai)下氣(qi)體(ti)稀薄程(cheng)度(du)(du)稱(cheng)為(wei)真空(kong)(kong)度(du)(du)（degreeofvacuum），通(tong)常(chang)用壓力值表示。因此(ci)真空(kong)(kong)包(bao)裝(zhuang)實際上不(bu)是完全(quan)真空(kong)(kong)的，采用真空(kong)(kong)包(bao)裝(zhuang)技術包(bao)裝(zhuang)的食品容(rong)器內的真空(kong)(kong)度(du)(du)通(tong)常(chang)在(zai)600-1333Pa。所(suo)以，又將(jiang)真空(kong)(kong)包(bao)裝(zhuang)稱(cheng)為(wei)減壓包(bao)裝(zhuang)或(huo)排(pai)氣(qi)包(bao)裝(zhuang)。