The Collaborative International Dictionary of English v.0.48:

Aporia \A*po"ri*a\, n.; pl. Aporias. [L., doubt, Gr. ?, fr. ?
   without passage, at a loss; 'a priv. + ? passage.] (Rhet.)
   A figure in which the speaker professes to be at a loss what
   course to pursue, where to begin to end, what to say, etc.
   [1913 Webster]