堂奥[ táng ào ]

⒈ 厅堂和内室。英the innermost recess of a hall;

⒉ 腹地。英the interior of a country;

⒊ 堂的深处，喻含义深奥的意境或事理。例无能老蝙蝠，乘夜出堂奥。——张来《夏日杂感》英profundity of thought or knowledge;