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