महाविनाश mahāvināśh

महान्, महा mahān, mahā (sanskrit)

(prefix) Great, illustrious.
Mighty, strong, big, large, ample, excessive, grievous.
Very, extremely, very much.

विनाश vināśh (sanskrit)

Utter destruction, disappearance, destruction, utter loss, ruin, death, annihilation.
(in particular) The destruction of the old world.