Yug युग Yugam युगं BG 8:17
Yug युग An age of the world.
There are 4 Yugs. Krit or Satya (T always pronounced softly), Treta, Dwaapar, and Kali.
The duration of each is said to be respectively 1,728,000 and 1,296,000 and 864,000 and 432,000 years of men.
The four together comprising 4,320,000 years of men which is equal to one MahaaYug q.v.
It is also supposed that the regularly descending length of the Yugs represents a corresponding physical and mortal deterioration in the people who live during each age. Dictionary p458.