My definition of a nerd is a person that obsesses over a particular subject to the point that it disrupts their social life. Jocks can be considered as nerds if they constantly think about sports and need to know the stats of numerous sports. Nerds don't have to be frail, pale skin intelligent people with glasses, but could be quite athletic and not very intelligent.
Hmm, the way I have always taken it, (all jokes aside) is...
A Nerd is someone who is strictly a no nonesence, by the book obsessed fanboy who will argue about the logic of a plot or technical possibilities of something real or other wise. he also pictures himself to be smart enough that the makers couldnt live without his advice to make things better and orderly to his perfect specifications!
A Geek is a more passive fanboy who obsesses for the fun of it, he could careless if two shows didnt follow a set cannon he still enjoyed it and probably pictures himself as eather one of the characters or RP's himself as part of the crew in place of another. his ideas he shares in hopes that the makers will consider them good enough to respond with an "attaboy" which would make thier day.
Then there is the Avatar, who has made a total RP personality just for the net, doesnt care about one thing or another in general, but still adds in their thoughts based on the RP/theme/avatar, they portray themselves as. They add in their comments just to see the reactions to thier "jokes/drama/tough guy act/flirty behavior."
A Snert/Noob/Naaf, is someone who only comments to whine about everything being too hard, expensive or are lazy to figure it out themselves. They are generally the first commentors lined up to complain about everything new that comes out, they hang around the the latest areas of interest asking what to do hoping to have another do it, or figure it out for them. They have librarys of walkthroughs and cheats that often equal the Library of Congresses contents...ok i jest on this one, but had fun writing it
To me, a nerd is an angry, narrow-minded, over-obsessed fanboi. He is not your fellow Trekkie or Whovian or whatever. He's that one guy with a superiority complex and believes himself to be "the one true fan." He thinks that no other individual on this planet can match him in knowledge over his obsession and firmly believes his word in the fandom is absolute. If you get even one minor detail wrong, he will devote every fiber of his being into over-correcting your mistake, hoping it will scar you for the rest of your life. A reminder that if you're EVER wrong, he'll be there...waiting...
By that definition, I've never liked nerds. And I never will.