A "medical device software”, refers to a computer application that meets the legal definition of a medical device and is not a part of any distinct product.
Medical Device Software
A Software SW either embarked into a medical device (i.e. MD, IVD, etc.) or intended to be used for a medical purpose without being part of a hardware medical device (Standalone MD SW). In both cases, this SW has to conform to the regulatory requirements of the Medical Device Directives (i.e. standard ISO62304 on MD SW lifecycle processes, etc.).