bí hiểm

== Vietnamese == === Etymology === Sino-Vietnamese word from 祕險. === Pronunciation === (Hà Nội) IPA(key): [ʔɓi˧˦ hiəm˧˩] (Huế) IPA(key): [ʔɓɪj˨˩˦ hiəm˧˨] (Saigon) IPA(key): [ʔɓɪj˦˥ him˨˩˦] === Adjective === bí hiểm unfathomable; mysterious