KALKI or Kalkin, Skt., lit. “white horse,” the tenth avātara, who is yet to appear. The white horse symbolizes the strength (of the horse) and the power (of the color white, which unites in its being all colors of the spectrum) that Kalki will possess. He will vanquish Yama, or Death, and will resolve all opposites as well as overcome darkness. He will be the divine man, at one with infinite divinity.
Source: The Encyclopedia of Eastern Philosophy and Religion: Buddhism, Hinduism, Taoism, Zen. Shambhala Publications, Inc.
External link: Kalki