to make out the meaning of (poor or partially obliterated writing, etc.)

to decipher a hastily scribbled note.

to discover the meaning of (anything obscure or difficult to trace or understand)

to decipher hieroglyphics.

to interpret by the use of a key, as something written in cipher

to decipher a secret message.

Obsolete . to depict; portray.

noun

clarification , construction , elucidation , exegesis , explication , exposition , illumination , illustration , interpretation