Elite (and Heroic Elite) is an item property present on certain items that will be available to players that defeat the Protectors of the Endless encounter (1st boss in the Terrace of Endless Spring) killing Protector Kaolan last.
According to item stats, it appears that "Elite" items will be 7 item levels higher than regular items. "Heroic Elite" items will be 7 item levels higher than Heroic items.
The Patch 5.2 Throne of Thunder raid will introduce a similar bonus tier called Thunderforged.
Example item levels