WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
the kind of intellectual who converts messages from a code to plain text
noun.
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)."