真(zhen)(zhen)空(kong)(kong)，這一術語譯自(zi)拉(la)丁文vacuo，其意(yi)義(yi)是虛無(wu)。其實(shi)真(zhen)(zhen)空(kong)(kong)應(ying)理解為(wei)氣(qi)體(ti)較稀(xi)薄的空(kong)(kong)間(jian)。在指定(ding)的空(kong)(kong)間(jian)內(nei)，低(di)于一個(ge)大(da)氣(qi)壓力(li)的氣(qi)體(ti)狀(zhuang)態統稱為(wei)真(zhen)(zhen)空(kong)(kong)。真(zhen)(zhen)空(kong)(kong)狀(zhuang)態下氣(qi)體(ti)稀(xi)薄程度(du)(du)稱為(wei)真(zhen)(zhen)空(kong)(kong)度(du)(du)（degreeofvacuum），通常(chang)用壓力(li)值表(biao)示。因此真(zhen)(zhen)空(kong)(kong)包(bao)(bao)裝實(shi)際上不是完全真(zhen)(zhen)空(kong)(kong)的，采用真(zhen)(zhen)空(kong)(kong)包(bao)(bao)裝技術包(bao)(bao)裝的食品容(rong)器內(nei)的真(zhen)(zhen)空(kong)(kong)度(du)(du)通常(chang)在600-1333Pa。所以，又將真(zhen)(zhen)空(kong)(kong)包(bao)(bao)裝稱為(wei)減(jian)壓包(bao)(bao)裝或排氣(qi)包(bao)(bao)裝。