1. not decoded or interpreted; remaining mysterious or unreadable

Examples

• The ancient script remained undeciphered for centuries.
• Archaeologists discovered undeciphered symbols on the cave wall.
• The message was written in an undeciphered code.
• Many undeciphered languages from antiquity still puzzle scholars.
• The undeciphered text held secrets of the lost civilization.
• Researchers are working to crack the undeciphered manuscript.