the highest ranking official responsible for irrigation and construction works in ancient East Asia (China and Korea)
Definitions (粵典–words.hk)
名詞
中國古代官職名，自西周始置，同司徒、司馬同屬於三公之一。司空係「司工」嘅假借，原本負責掌管國家重大水利、營建之類土木工程。後來漢成帝將御史大夫一職改為大司空，但職責就變為監測百官；明清時就係工部尚書嘅別稱。 the head of the ministry of construction affairs in ancient China
Definitions (Wiktionary)
noun, historical
Minister of Works (one of the three most important official posts during the Han Dynasty)