Turnaround in filmmaking is the use of outside assistance to resolve problems preventing a film project from completing its development phase and entering the preproduction phase.
In the case of the filmmaking process, the transfer of the film project from development hell, at one studio, leading to the project receiving a green light to begin pre-production, at another studio, is referred to as a 'turnaround' for that film.
A 'turnaround' or 'turnaround deal' is occasionally used to describe an arrangement in the film industry whereby the production costs of a project that one studio has developed are declared a loss on the company's tax return, thereby preventing the studio from exploiting the property any further.
The rights can then be sold to another studio in exchange for the cost of development plus interest.
[1] Michael Cieply defined the term in The New York Times as "arrangements under which producers can move a project from one studio to another under certain conditions".