神秘 (shén mì): ลึกลับ

Many mysterious legends are hidden in that old castle, attracting quite a few explorers to go and investigate.

He smiled mysteriously, said nothing, and turned to leave the room.

A mysterious mist always shrouds the depths of this forest, and few people dare to walk in alone.

After receiving a mysterious phone call, she hurried out and even forgot to take her bag.

Scientists have been studying this mysterious phenomenon, but so far they haven't found a reasonable explanation.