A typical semi nerd may play a console video game such as medal of honor, or Halo, they have many friends of both genders, but usually play two to no sports.
It could be said that they aren't nerds but they do nerd related activities in a 'cool' way.
Semi Nerd: Halo bro, get it right.
Nerd: Im sooo smarter than you, what is (27x11)/cosine(2+1)
Semi Nerd: Umm, can you use it in a sentence?