1. A gaming buddy who will often visit s friend's house, and play his friend's video games (with his friend)as the Player 2, or second player in 1 vs 1 matches. These may or my not (but often are), games said player 2 does not own and is often bad to mediocre at. A Player 2 can be characterized by being owned by his friend many times in any said game for the first few visits, but then gets to the point when he/she wins upwards of 40% of the time. These are often close friends, and don't stay sore about losing. However, their friend may cheat against them, or get them frustrated by causing their character (or whatever they play as in the game) to consistently epic fail through said Player 2. A good player 2 will eventually get good at said games, but will never NEVER ask for their friend to go easy on them unless they are not having fun.
2. More simply, the second player in a two or more player video game.
Player 2 :
I have no X Box, but I was playing Halo 3 at my friend's house a few times. He kept in sniping me and using invisibility and bullshit to kill me, but in the end I killed him like five times. I came over the next week, and after a while I got a three kill streak with the gravity hammer, and was harassing him using the hornet, hut he still won.
My other friend came over my house, and we played Star Wars Rebel Strike: Rogue Squadron 3 on my blue cube. I shot him down like four times in one game, then in rampage mode my score was three times his. About a few years later, he manages to beat me in rampage sometimes, and can beat me in a dog fight if he cheats with lock on missiles, or if I bs and fly dramatically.
Geek speak for "significant other"
My gf and I play Wii together, so I started calling her my Player 2.