Why are some bodies of water called seas even though they are technically gulfs?

The premise that some bodies of water are "technically" gulfs but are called seas is a reflection of the fact that geographical nomenclature is far from uniform. There is no strict scientific standard that mandates a specific name based solely on a body of water's physical characteristics.1

In geography, a gulf is defined as any large coastal indentation or reentrant of an ocean, regardless of its size, depth, or configuration. Because this definition is broad, many bodies of water that function as gulfs are historically or culturally labeled as seas. For example, the Sea of Azov is geographically a gulf of the Black Sea, yet it retains the name "sea" due to historical convention.1

Ultimately, the naming of these features often depends on human factors, such as historical, political, or ecological significance, rather than rigid geological classification. Consequently, terms like "sea," "gulf," "bay," and "fjord" are often used interchangeably or inconsistently across different regions of the world.21