He has an idea for a movie.

[WilliamTaft]

An example sentence using "idea" in The Britannica Dictionary: He has an idea for a movie.

What does it mean?

 

[Tdol]

Nothing has been made, but he has something that he thinks could be made into a movie- it could be an original story- even if not written yet - or something like a book that he thinks could be adapted into a movie.

 

[Rover_KE]

Here's my idea for a film/movie — a family decides to go on holiday but unfortunately their young son gets left behind and nobody notices he's missing. Two thieves – Scotsman Nick McAshe and Dutchman Rob de Loot – break into the house to ransack it, but the boy thwarts their evil plans. I'm going to call it 'Home Alone' ...

What's that you say? It's already been done? Rats! I could have made millions if I'd thought of it sooner.