de ‧ ci ‧ pher /dɪˈsaɪfə $ -ər/ BrE AmE verb [transitive]
1 . to find the meaning of something that is difficult to read or understand ⇨ indecipherable :
She studied the envelope, trying to decipher the handwriting.
2 . to change a message written in a ↑ code into ordinary language so that you can read it SYN decode
—decipherment noun [uncountable]