The Pomeranian is named after a stretch of seaside, and the dogs that first carried the name were much bigger than today's.
Pomerania is a region on the south coast of the Baltic, spanning northeastern Germany and northwestern Poland. Etymonline traces its name to Medieval Latin Pomerani, a Slavic tribe of the area. That name comes from Polish po morze, "by the sea." Germans call the region Pommern, and Poles call it Pomorze.
The dog's name is older than many people expect. Etymonline dates Pomeranian, for a small Spitz-type dog, to 1760. Spitz is German for "pointed," after the dog's tapering muzzle.
The early dogs were not small. Wikipedia says the dogs in Thomas Gainsborough's paintings reportedly weighed 30 to 50 pounds. Mental Floss says early Poms averaged around 30 pounds and were all white until the 19th century. Wikipedia credits Queen Charlotte with bringing two of them, Phoebe and Mercury, to England in 1767, though it flags that claim as needing a citation. Gainsborough painted both dogs.
The shrinking is tied to Queen Victoria. Mental Floss says she fell for the breed in 1888, when she imported four Pomeranians from Italy, among them a sable male named Marco. Wikipedia, which flags its own import account as needing a citation, says Marco was first exhibited in 1891, reportedly at 12 pounds. She possibly registered him as "Windsor's Marco." It also reports that the breed's size fell by half during her lifetime.
Clubs followed. The first breed club was set up in England in 1891, and a standard was written soon after. The American Kennel Club first registered the breed in 1898 and recognized it in 1900.
Two Pomeranians later earned a place in a famous disaster. Wikipedia says they were among only three dogs to survive the sinking of the Titanic.
The name now describes where the dog's ancestors lived, not what the modern dog looks like. A sturdy dog of the Baltic shore became a lapdog and kept its seaside name.