Noun
English Wikipedia has an article on:working titleWikipedia
working title (plural working titles)
The temporary name of a product or project (such as a film or video game), when under development; often changed when released.
Synonyms: production title, tentative title
I'm appearing in a new Working Title film. It's going to be my first big film and I'm really excited. The film itself will feature Simon Pegg, Jim Broadbent, Timothy Dalton and myself. Filming has just started. Joseph McManners
Jigsaw Lady is the working title of a science fiction novel I've had in my head for darn near 15 years. I think I'll start work on it next year (in all my spare time) but I'd like to get it finished some day. Raymond E. Feist