Cryptic
Part of speech: adjective
Definition: Having hidden meaning. Mystified or of an obscure nature. Involving use of code or cipher.
Part of speech: noun
Definition: A cryptic crossword.
Incomprehensible
Part of speech: adjective
Definition: impossible or very difficult to understand
Example sentence: That's the way it is with poetry: When it is incomprehensible it seems profound, and when you understand it, it is only ridiculous.