Today what passes as emo is mostly bullshit, its not what emo was or what the name came from. But yes it is short for emotional. and to picture an "emo kid" picture your alterna hipster for the 00's. tight pants trendy hat style of the season and tight shirts preferably thrift store, black rim glasses (though these are used all over the place) and shaggy hair must be black.
Now I fall in to that category of style of dress (minus the hat) But I'm punk/hardcore skate/snowboard guy with geek streaks since being geeky pays my bills.
for a full break down of "emo" and what it really is and its history please review
http://www.fourfa.com/
note: this is not the pre-packaged hot topic mall emo you see all the highschool kids looking like and listening to.