There are as of this moment 1,180 definitions for the term, bloody kids these days, I don't know.... however I quite like this one:
The most over-defined word on urban dictionary!
bob: omfg! have you seen how many definitions there are for emo on urban dictionary?
joe: no how many???
bob: like over 800!
joe: holy shit lets add another one just
for the heck of it!