[stronglikedan]

From what I've seen in the comments, it's definitely ELO, if not through ubiquity alone. Happens to the best of 'em!

[catlifeonmars]

Elo is nicer as it gives a nod to the inventor, no?

[lmm]

Some say the greatest compliment a mathematician can be paid is when a concept that bears their name is so ubiquitous that we no longer capitalise it. (E.g. Abel with the abelian group).