Gun pills: why is it called a .38 Special?

Why the .38 Special is defined as "Special", and is  a .38, even if it shoots a .357 caliber bullet?

Profile of a Cartridge: History and Development of the 38 Special

38 Special

Pierangelo Tendas

5.11 Kubaton: the tactical pen for everyone

38 S&W Variants and History - Shooting Times

America's Military Revolvers An Official Journal Of The NRA

38 Special

2023 October 25 The Paul Friedrich Collection of Firearms & Gold

Snub nose revolver hi-res stock photography and images - Alamy