A fictional phenomenom where waves of energy combine in a continual loop (cascading). In essence, the energy multiplies out of control. See Resonance Reversal.
The primary event leading to the other major events in the popular computer game Half-Life. It was caused by Gordon Freeman.
After the resonance cascade, aliens began to fill the Black Mesa Research facility and kill off the science and security personel. Things got worse over the years, as a new race of aliens named "Combine" came along and began killing people and sucking up Earth's natural resources. Because of all this, we can blame Gordon Freeman.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).