A rather annoying word whose use in certain situations has greatly increased recently.
Kind of like the word "shit," "fail" is used by people who don't stop to think of a better word to use, making them pretty much useless to society.
A kid falls off a bike.
Douche bag: Fail!
Person that can think rationally: Stop saying "fail" at people who weren't even trying to succeed at anything in the first place.
"Fail" is a word that is more than often overused online. Unfortunately it has spewed into mainstream society and now is being used in every day life, much like "epic".
People who "fail" generally are not even trying to accomplish anything, or they simply do something different than you. This word is most commonly used by annoying teenagers (who put a bad reputation on gaming), who shout "FAIL!" every time someone makes a slight error.
If you point out an obvious flaw by saying "FAIL" you're obviously a failure yourself for having lack of logic.
Kid: I just tripped because someone...tripped me.
Idiot who doesn't use logic to realize it wasn't the kids fault for being tripped, it was actually the other persons fault: FAIL!