IPA: /ˌʌn.dɪˈsaɪ.fərd/
KK: /ʌnˈdɪsəˌfaɪərd/
Something that has not been understood or interpreted yet.
The ancient script remains undeciphered despite many attempts by experts.
Undeciphered → It is formed from "un-" (meaning not) and "decipher" (from Latin "decipherare", where "de-" means down or from and "caper" means to seize or take). The word "undeciphered" means not able to be seized or understood, indicating something that cannot be decoded or interpreted.
Think of something that is 'not' ('un-') able to be 'understood' ('decipher') — that's why undeciphered means it cannot be decoded.