Thayer's Greek Lexicon

 1. a saying out of the usual course or deviating from the usual
manner of speaking
  1) a current or trite saying, a proverb
2. any dark saying which shadows forth some didactic truth
  1) esp. a symbolic or figurative saying
  2) speech or discourse in which a thing is illustrated by the use
of similes and comparisons
  3) an allegory
2c1. extended and elaborate metaphor