The abriviation for "Dragon Longsword" on the online game RuneScape. It's very powerful, but sadly not the most powerful weapon on RuneScape. Can be bought in a store in the lost city of Zanaris, which is inhabited by strange creatures from other realms. Sold by a fairy along with a Dragon Dagger. It costs 100000gp(100k).

People seem to more often just buy one from other players, as to get to the Zanaris marketplace they have to give a doorman a cut diamond. Even though by contrast to the dlong it doesn't cost much. (It's not even 1k)