This is a portlet, which shows a content item with it's default view.
It's inspired by the Plone's full view, therefore the name - and it shares the same codebase for the fullview_item view (actually from collective.fullview/plone.app.contenttypes).
Note
Plone 4 / Archetypes users, if you want to display a content item/folder with the full view as default view, please don't use the one provided by CMFPlone but use instead the one provided by the collective.fullview addon or by plone.app.contenttypes.
At time of this writing, for plone.app.contenttypes 1.1.x, the fullview is provided by the branch 1.1.x-thet-unifiedlistings, for 1.2.x the fullview is provided with the release 1.2a6