terra incognita /ˈterəˌɪnˌkɑːgˈniːtə/ noun plural terrae incognitae /ˈterˌaɪˌɪnˌkɑːgˈniːˌtaɪ/ /ˈterəˌɪnˌkɑːgˈniːtə/
noun
plural terrae incognitae /ˈterˌaɪˌɪnˌkɑːgˈniːˌtaɪ/ Learner's definition of TERRA INCOGNITA
[count] formal
: a place that has not been discovered or that is unknown未发现的地域;未知领域 —
often used figuratively常用作比喻