Continent

A continent (or landmass) is the largest geographical subdivision of a planet or world. Continents, which can actually be parts of larger continents, are broken down into regions or zones.

Azeroth's geography
The earliest information about landmasses is brief. A huge war between the Titans and the Old Gods "ripped Azeroth into new shapes".

At the time of the War of the Ancients, 10,000 years ago, Azeroth had one singular continent called Kalimdor. The Sundering broke apart this landmass into various continents and islands. Currently, the ancient landmass known as Kalimdor would be called a supercontinent since all the land was once a part of it.

The number of continents has grown and shrunk as time has gone by. This is due to the discovery of new lands, the importance of those lands, and maybe politics. Currently on Azeroth, there are three large continents in the game: the Eastern Kingdoms (formed of three subcontinents) in the east, Kalimdor (formed of three subcontinents) in the west, and Northrend in the north. These continents are bordered by the Great Sea which seem to occupy the whole of the planet.

Azeroth's continents

 * Eastern Kingdoms
 * Lordaeron
 * Sometimes, Quel'Thalas
 * Khaz Modan
 * Azeroth
 * Kalimdor
 * Northern Kalimdor
 * Sometimes, Teldrassil
 * Central Kalimdor
 * Southern Kalimdor
 * Northrend

Azeroth's "subcontinents"

 * Quel'Thalas (part of Lordaeron)
 * Teldrassil (described as an island, a mid-sized island, an island continent or a giant tree )

Other important landmasses

 * Pandaria (island)

The Undermine
The Undermine was already in the early World of Warcraft Betas, but not as a city on a island, but as a continent south of Kalimdor, but there was only water there and nothing else.

The Undermine might be added as a new continent later on.

Miscellaneous landmasses

 * South Seas (contains many islands)
 * Ominous island

Outland's continents
Outland does not have continents in the traditional sense. Outland is itself a single continent that represents the remnants of what was once Draenor. Draenor may have had more than one continent before it was shattered, but these land masses have names lost to the mists of history.

The Elemental Plane's continents
The Elemental Plane has one continent: Deepholm.

The Emerald Dream's continents
The Emerald Dream and Azeroth "are quasi-duplicates of each other".

Fourth Expansion continent
Ghostcrawler stated in an interview that the fourth expansion for WoW after Cataclysm will likely be set on a new continent. It remains unknown what the new continent will be.