Source : Webster's Revised Unabridged Dictionary (1913)

Agnoiology \Ag`noi*ol"o*gy\ ([a^]g`noi*[o^]l"[-o]*j[y^]), n.
   [Gr. 'a`gnoia ignorance + -logy.] (Metaph.)
   The doctrine concerning those things of which we are
   necessarily ignorant.