A thick penis has an above average girth, measuring more than 14cm in an adult male.
Thick penis - is a larger girth better?
An internet search concerning "thick penis" resulted in a one sided discussion: is a larger penis girth really better than a smaller girth.
Penis girth from a medical point of view
From a medical pint of view, it is true that a shorter and thicker penis is more pleasurable for women than a long an thin penis. The areas responsible for the woman's stimulation are located mostly in the area of the clitoris, as well as the frontal area of the vagina, making a short, thick penis advantageous over a long, thin penis.
In internet forums, this is reflected in a change in topics - while the penis length used to be the predominant subject, it has now shifted to girth.
Average penis girth
The average penis girth in the adult male is between 12 and 14cm. Again, just as with the lengths, there are major differences in populations. A penis girth of more than 18 cm is considered unusual and is considered as rather painful for women during sex.