idea in WordNet English dictionary

1. an approximate calculation of quantity or degree or worth
   "an estimate of what it would cost"; "a rough idea how long it would take"
   estimate  estimation  approximation  idea 
   
2. the content of cognition; the main thing you are thinking about
   "it was not a good idea"; "the thought never entered my mind"
   idea  thought 
   
3. your intention; what you intend to do
   "he had in mind to see his old teacher"; "the idea of the game is to capture all the pieces"
   mind  idea 
   
4. a personal view
   "he has an idea that we don't like him"
   idea 
   
5. (music) melodic subject of a musical composition
   "the theme is announced in the first measures"; "the accompanist picked up the idea and elaborated it"
   theme  melodic theme  musical theme  idea