What is considered a short height for a man? and what is average height?

Depends . . .: Average height depends upon genetics, ethnicity, nutrition and other intangibles. Check out http://www.Disabled-world.Com/artman/publish/height-chart.Shtml ; http://en.Wikipedia.Org/wiki/human_height for an idea of how average height varies around the world. Short stature might be those less than 2nd percentile or so. In the states, we tend to notice less than 5'6" as short.