I hereby propose a new technical term for a type of application to software developers and power users.
Comrade
A comrade is an app (an app is a self-contained application usually for tablets or phones) that usually comes with the OS or is available from the OS vendor and acts as a calendar, address book or email program, i.e. one of the three that are now typically synced with a cloud.
Comrades are sometimes configurable and are often meant to sync only with the OS vendor’s own cloud.
The iOS calendar comrade
Microsoft’s calendar comrade
BlackBerry’s Contacts and Calendar comrades (icons)
A comrade is also defined by its limitations. A comrade is really an app that was created just because it was needed. It doesn’t have any special features. Microsoft’s comrades on Windows 8 and Windows RT are typical comrades in that they basically don’t have any features. (In fact they don’t even work as intended.)
Microsoft Outlook, which also does email and keeps an address book and calendar is not a comrade (too many features).
Apple’s email program Mail.app is also not a comrade (one of the defined purposes but has clearly been designed to be a good email program and not just a necessary one).
BlackBerry’s BlackBerry Hub is not a comrade, but BlackBerry 10’s Contacts and Calendar apps are.