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?

A History of the Iconic .38 Special - The Shooter's Log

380 vs 38 Special Berry's Bullets Pistol Ammo Comparison

38 Special Ballistics - Velocity, Energy & Bullet Drop

Beginning Revolvers - Colt & Smith

Optics, Page 8

GUNSweek

Technics

Sold at Auction: 1947-1948 Colt Official Police .38 Special Double

S&W Snub-Nose Bicycle Revolvers — Elegant and Vintage - Firearms News

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GUNSweek

AK-47, Page 4

856 UL, Double Action .38 Special Revolver With 2 in Barrel - 6

Lot - SMITH & WESSON MODEL 60 .38 SPECIAL REVOLVER

Wheelgun Wednesday: Silencing the Gap – Part 3 -The Firearm Blog