Why are they called meeting minutes?

The reason that meeting minutes are called minutes rather than notes or a summary isn't known for sure. However, the prevailing theory is that it doesn't have anything to do with minutes, as in the measure of time, but instead comes from the Latin minuta scripta, meaning small writing.

This comes from the fact that scribes in monestaries would write in a small script in order to save ink and parchment, and minuta turned into minute. It's actually related to minute, as in small, rather than minute, the measure of time.