idea

(music) melodic subject of a musical composition.

“the accompanist picked up the idea and elaborated it”

An approximate calculation of quantity or degree or worth.

“a rough idea how long it would take”

The content of cognition; the main thing you are thinking about.

“it was not a good idea”

Your intention; what you intend to do.

“the idea of the game is to capture all the pieces”

A personal view.

“he has an idea that we don't like him”