lesson in WordNet English dictionary

1. punishment intended as a warning to others
   "they decided to make an example of him"
   example  deterrent example  lesson  object lesson 
   
2. a task assigned for individual study
   "he did the lesson for today"
   lesson 
   
3. a unit of instruction
   "he took driving lessons"
   lesson 
   
4. the significance of a story or event
   "the moral of the story is to love thy neighbor"
   moral  lesson