真(zhen)(zhen)空(kong)，這(zhe)一(yi)術語(yu)譯自拉丁文vacuo，其意義是虛無。其實真(zhen)(zhen)空(kong)應(ying)理解(jie)為氣(qi)體較稀(xi)薄(bo)的空(kong)間。在指定(ding)的空(kong)間內，低(di)于一(yi)個大(da)氣(qi)壓力的氣(qi)體狀態(tai)統(tong)稱(cheng)為真(zhen)(zhen)空(kong)。真(zhen)(zhen)空(kong)狀態(tai)下氣(qi)體稀(xi)薄(bo)程度(du)稱(cheng)為真(zhen)(zhen)空(kong)度(du)（degreeofvacuum），通(tong)常用壓力值表示。因此真(zhen)(zhen)空(kong)包(bao)裝(zhuang)實際(ji)上不是完(wan)全真(zhen)(zhen)空(kong)的，采用真(zhen)(zhen)空(kong)包(bao)裝(zhuang)技術包(bao)裝(zhuang)的食品容(rong)器內的真(zhen)(zhen)空(kong)度(du)通(tong)常在600-1333Pa。所以(yi)，又(you)將真(zhen)(zhen)空(kong)包(bao)裝(zhuang)稱(cheng)為減壓包(bao)裝(zhuang)或排氣(qi)包(bao)裝(zhuang)。