A divisional patent application (sometimes referred to as a divisional application or simply a divisional) is a type of patent application which contains matter from a previously-filed application (the "parent" application). Whilst a divisional application is filed later than the parent application, it may retain its parent's filing date, and will generally claim the same priority.
Divisional applications are generally used in cases where the parent application may lack unity of invention; that is, the parent application describes more than one invention and the applicant is required to split the parent into one or more divisional applications each claiming only a single invention. The ability to file divisional applications in cases of lack of unity of invention is required by Article 4G of the Paris Convention.[1]