arcane(understood by only a few; obscure) adjective [UK: ɑːˈk.eɪn] [US: ˌɑːrˈk.eɪn]
mysterious(of unknown origin) adjective [UK: mɪ.ˈstɪə.rɪəs] [US: ˌmɪ.ˈstɪ.riəs]This place has a mysterious atmosphere. = Det här stället har en mystisk atmosfär.
unearthly(strange or mysterious) adjective [UK: ʌn.ˈɜːθ.li] [US: ʌ.ˈnɝːθ.li]