Here's why this term was used:
* Narrowness: Sounds are often narrow bodies of water, like straits or channels, which could be navigated by swimming or wading across.
* Passage: The word "sund" also conveyed the idea of a passage, a way to travel through or across a body of water.
Over time, the word "sund" evolved into "sound" in English, and this term became commonly used to describe certain types of waterways, especially those that:
* Connect larger bodies of water: For example, the Long Island Sound connects Long Island to the mainland.
* Are narrow and often shallow: The Puget Sound is a series of inlets and channels that are relatively narrow and shallow compared to the open ocean.
* Are typically sheltered: Many sounds are protected from the open ocean by landmasses, making them calmer and more navigable.
Therefore, the term "sound" describes a specific type of waterway, characterized by its narrowness, shallowness, and often its role as a passageway between larger bodies of water.