What does ELO stand for ?

[76561198849092502]

Thank you.

[Kaizen]

It doesn't stand for anything at all, because it's not an acronym. It should be "Elo" rather than "ELO." The Elo rating system is named after the Hungarian-American physics professor (and 8-time state champion chess master) Arpad Elo, who originally devised his rating system around 1960.

[Crazy Fat Gundamn]

Electric Light Ochestra

[-=RelakS=-]

Hehehe, then it is even misprinted, as his name is Élő Árpád :D (his family name comes first)
Yes, with that many diacritics. I know that it is really hard to type in english keyboards, and usually we can read withot them too, but if it mentioned, I wanted to write this down.
BTW, élő means living, as living animal.