What is a "Bomb Cyclone"?

One term you may have heard from the storms on the west coast is "Bomb Cyclone". 

Bomb Cyclone is actually short for a meteorological term, Bomb Cyclogenesis.

This is when an area of low pressure rapidly intensities, dropping 24 millibars in 24 hours. 

So rather than a noun like it's been used as, it's more of an adjective, describing the process happening with the area of low pressure. 

When a low pressure intensifies like this, it can bring heavy rain and/or heavy snow, and strong wind.