How do you define an "application" for app portfolio mgt purposes?

Murphy_p_small   Once apon a time ... the definition of an application was easy - firms built accounts payable, general ledger, purchasing, order entry, and other applications to meet the automation needs of the business. The applications were written as monolithic collections of functionality that were dedicated to accomplishing key business functions and had relatively clear boundaries.

However, over the years, technology shifts have resulted in "applications" that don't fit the earlier simplistic definitions. DLLs, Services / SOA, ASPs and Software-as-a-Service (SaaS) all bent the definition of an "application" from its previous form. Looking forward, Cloud computing promises to alter the definition once again.

The definitions of an application thus far share a common catalyst - they all have some linkage to the technology components that comprise the application. But an emerging application management discipline - application portfolio management - calls for yet another twist in the story - how do we define an application for the sake of portfolio management?

With the goals of greater business transparency into the existing portfolio of applications/assets so they can be inventoried, managed, rationalized, streamlined, and governed more effectively - how do you (or would you) define an application for the purposes of APM? I have my thoughts - which I will share once the blogosphere has spoken - I don't want to color what promises to be an interesting and diverse set of opinions. Please share your thoughts freely.