idea

noun

1. the content of cognition; the main thing you are thinking about"it was not a good idea"
2. your intention; what you intend to do"he had in mind to see his old teacher"
3. a personal view"he has an idea that we don't like him"
4. an approximate calculation of quantity or degree or worth"an estimate of what it would cost"
5. (music) melodic subject of a musical composition"the theme is announced in the first measures"