“In a medical context, short stature is typically defined as an adult height that is more than two standard deviations below a population’s mean for age and gender, which corresponds to the shortest 2.3% of individuals in that population.[1]”
“The distributions of the heights of males and of females have standard deviations of approximately 2.8 inches.”
“According to the Centers for Disease Control and Prevention (CDC) , the average age-adjusted height for American men 20 years old and up is 69.1 inches (175.4 centimeters). That’s about 5 feet 9 inches tall.”
5’9”-2(2.8”)=5 feet 3.4 inches
“According to a 2018 report from the Centers for Disease Control and Prevention (CDC), the average height among all American women, age 20 and up, is 5 foot 4 inches tall.”
That’s pretty close to my initial guess that short would be anything equal to or less than average female height for that region.