That's the median. The "average" (when used undecorated/unspecified) generally means the mean.

A distribution which is biased towards high-side outliers (such as wealth or income) will generally have more than half of the population below the mean.

It's not at all obvious to me that general intelligence has such a distribution (and I can think of plenty of physical mechanisms [injury, disease, malnutrition during development] by which the opposite could easily be true).

> The "average" (when used undecorated/unspecified) generally means the mean.

I wouldn't say that. Most population statistics--think "average" wages and the like--tend to use median. And when we're talking about intelligence, this isn't something that is readily quantifiable with a number. IQ is explicitly normalized so that 100 is median, and 110 is one standard deviation above median. "mean IQ" isn't a meaningful concept. Given that we can't even measure "mean intelligence", average intelligence tends to mean median intelligence in practice.

That's the median, and depend on the distribution, average and median could be different.

That said, the GP is just being obtuse. I'm not sure if he meant intelligence is non bell-shaped or some other reasons and I'm dumb too :-).

Median Vs mean, median has exactly half above/below it, the mean can be nearer the extremes if the distribution is unbalanced.

Not the person you responded to, but the quantity for which half are below and half are above (+-1) is called "median".

Which is one of three forms of averaging ... ?

Mean, median and mode. Though it's true that people usually mean 'mean' when they say 'average'.