Gosu(고수) is a computer gaming term usually used to refer a person highly skilled in multiplayer game like Starcraft, Warcraft III (RTS), Counter-Strike (FPS) and others. It has a Korean origin and since South Korea has one of the largest online gaming[1] communities the term was adopted by gaming communities in many countries including USA, Germany, France and Russia
Origin

In Korean, word gosu (Hangul: 고수, literally a high hand) is used for a person with great skill, usually in martial arts or in baduk (Go). In Gyeongnam province dialect gosu also has a meaning "leader"[2]. The word is partially derived from the Chinese word gaoshou and similar to the Japanese word jouzu. There is an urban legend saying that term gosu originated from Starcraft community as an acronym for "God Of Starcraft Universe" or "Guardian of Starcraft Universe". However, this is actually a backronym, as the term has long been applied to martial arts experts and players of other multiplayer games including first-person shooters like Counter-Strike. It is most likely that Starcraft players were among the first gamers to adopt the Korean word with a new meaning.

Related terms

Even though not so popular there are also several other commonly used Korean words for describing gamers with various skill levels. Jungsu stands for "a moderately good player", hasu for "a mediocre player" or "a person with no skill" and chobo for "a novice player". "Hasu" and "chobo" are the same skill level, but "hasu" is a polite/technical way of describing it, and thus implies the speaker has a general respect for the person as a human, or at least not a lack thereof. "Chobo" is a more insulting way of describing the player, implying the speaker looks down upon the person they are describing. An English equivalent would be newbie or noob.