Alternatively spelled "Ka'wak". One of the 4 Bacabs in Mayan mythology, this being holds up the south corner of the sky. Its color is red.
Some archaeologists, translating the word as "thunder", "lightning" or "rain", have determined Cauac to be a sky or rain god. Others, citing depictions of it with vegetation sprouting from its head, have declared it to be mountain or cave deity. It is usually referred to as a "monster" or "dragon".
Cauac is the 19th day of the Tzolkin calendar cycle.
Source: Taylor, Dicey. "The Cauac Monster." http://www.mesoweb.com/pari/publications/RT04/Cauac.pdf