Definition of Point size:
The size of a typeface, measured in points.
Distance (in points) from the highest ascender to the bottom of a descender of a print type. Used in commercial and computer printing in UK, USA, and other countries, except mainland Europe where type size is expressed in Didot points or as the height of capital (uppercase) letters in millimeters. Some countries (notably Germany and Japan) use the metric unit Q.
Meaning of Point size & Point size Definition