the GNU version of the Collaborative International Dictionary of English
n. One who deciphers.
The Century Dictionary and Cyclopedia
n. One who interprets what is written in ciphers, or reads what is written obscurely.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. the kind of intellectual who converts messages from a code to plain text
n. a reader capable of reading and interpreting illegible or obscure text
Word Usage
"Sibylline Leaves of 1817, in the title of which is implicit the same play of meaning suggested by Mary's authorial persona, self-characterized as the "decipherer" of these discoveries in the "slight Sibylline pages" (pp. 3, 4)."