What is "calabarzon"

n. An administrative region of the Philippines, including the provinces of Cavite, Laguna, Batangas, Rizal, and Quezon.

Calabarzon , formally known as Southern Tagalog Mainland and designated as Region IV-A, is an administrative region in the Philippines. The region comprises five provinces: Cavite, Laguna, Batangas, Rizal, and Quezon; whose names form the acronym CALABARZON. Its regional center is Calamba in Laguna.

Situated just south of Metro Manila in southwestern Luzon, the region is the most populous in the Philippines, having inhabitants in , and is also the country's second most densely populated. Prior to its creation as a region, Calabarzon, together with Mimaropa, formed the historical region known as Southern Tagalog, until they were separated in 2002 by virtue of Executive Order No. 103.

The region is home to some of the most important Philippine historical figures, most notable of which is the Philippines' national hero, Jose Rizal, who was born in Calamba.