# What does “chi” mean and come from in “chi-squared distribution”?

What does "chi" mean and come from in "chi-squared distribution"? Does "chi" mean a random variable with a standard normal distribution? Thanks!

• +1 A couple of tidbits: Early on, the distribution of the square root of a chi-squared r.v., the chi distribution ($\chi$-) was more widely used than now; useful for standard deviations. E.g. you can occasionally see in old papers or books people writing about the $t$ distribution as the distribution of the ratio of a normal to an independent (scaled) chi. One advantage of it (but not the original motivation for it) was that the normal approximation kicks in much faster (this is pre-Wilson-Hilferty); handy when tables tended to be quite limited. – Glen_b Jun 1 '13 at 0:35