Definitions for "Yuga"
Keywords:  treta, satya, kali, dwapara, krta
Any one of the four ages, Krita, or Satya, Treta, Dwapara, and Kali, into which the Hindoos divide the duration or existence of the world.
an age [there are four yugas: the satya (or krta) , treta, dvapara and kali].
an age of the world. Four ages are described in the Vedas: Krta or Satya, Treta, Dvapara, and Kali. The duration of each yuga is said to be respectively 1,728,000; 1,296,000; 864,000; and 432,000 years. The descending numbers represent a corresponding physical and moral deterioration of mankind in each age. The four yugas comprise an aggregate of 4,320,000 years and constitute a maha-yuga, or great yuga.
Keywords:  era, period, time
an era, then, a period of time
Keywords:  million, years
1.8 million years