A 'bomb cyclone,' explained

We've been warning for two days now that a major storm would develop along the East Coast and intensify so rapidly that it could earn a place in the record books. We were the first to call it a "weather bomb" or "bomb cyclone," and now that that term has taken off in the broader media, it's important to understand just what it means. 
"Bomb cyclone" may seem like an obscure expression invented by meteorologists for attention, or to describe some sinister atmosphere terrorism plot, but it's