See more at Wikipedia.org...

v. slog, hit hard; progress slowly and ploddingly; work persistently, toil

(n.)
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.
  

[Hindu] One of the four ages of the world into which, according to Hindu cosmology, the mundane time is divided. The names of the four ages are 1) Krita-yuga, 2) Treta-yuga, 3) Dwapara-yuga and 4) Kali-yuga. It is said that Dharma or virtue (which is symbolically represented by a Bull) walks on all the four feet in Krita yuga and with the advent each subsequent Yuga, it loses one foot. Thus, it walks on 3 feet in Treta and 2 feet and Dwapara and so on.

Yuga (Sanskrit) Age; an age of the world, of which there are four -- satya yuga, treta yuga, dvapara yuga, and kali yuga -- which proceed in succession during the manvantaric cycle. Each yuga is preceded by a period called in the Puranas, sandhya (twilight, transition period, dawn) and followed by another period of like duration often called sandhyansa (a portion of twilight). Each of these transition periods is one-tenth of its yuga. The group of four yugas is first computed by the divine years or years of the gods -- each such year being equal to 360 years of mortal men. Thus we have, in divine years:
1. Krita or Satya Yuga . . 4,000 Sandhya . . . . . . . . 400 Sandhyansa . . . . . . 400 4,800 or 1,728,000 mortal years
2. Treta Yuga . . . . . . . 3,000 Sandhya . . . . . . . . 300 Sandhyansa . . . . . . . 300 3,600 or 1,296,000 mortal years
3. Dvapara Yuga . . . . . . 2,000 Sandhya . . . . . . . . 200 Sandhyansa . . . . . . . 200 2,400 or 864,000 mortal years
4. Kali yuga . . . . . . . 1,000 Sandhya . . . . . . . . 100 Sandhyansa . . . . . . 100 1,200 or 432,000 mortal years
Total: 12,000 a Mahayuga or 4,320,000 mortal years
to be continue "Yuga2 "