Why is a train called a "dog"? - briefly
The term "dog" for a train originates from railway slang in the United Kingdom, where it was used to describe a slow-moving or stopping train that would block the line and cause delays for faster trains. This usage is believed to have stemmed from the idea of a dog lying in the path as an obstacle.
Why is a train called a "dog"? - in detail
The term "train" as applied to a sequence of railway carriages has an interesting etymological history, one that sheds light on the cultural and technological developments of the 19th century. The use of the word "train" in this context is not directly related to the animal dog but rather evolved from its original meaning associated with trailing or following.
In medieval times, "train" referred to a long robe or skirt that trailed behind a person as they walked. This sense of something following closely behind another object or entity persisted through centuries. When early railways were developed, the term was adopted to describe the series of carriages that followed one another in a sequence, much like a procession or a line of people walking in succession.
The first known use of "train" in reference to railway carriages appeared in 1825, just as railways were beginning to transform transportation and industry. The term caught on quickly due to its intuitive nature; it aptly described the linear arrangement and movement dynamics of the carriages. Over time, this usage became standardized, and "train" has since been universally accepted as the term for a series of connected railway vehicles.
This linguistic evolution highlights how language adapts to new technologies and innovations. The historical shift from describing clothing to transportation illustrates the flexibility and descriptive power of language. Today, while many may not be aware of its origin, the term "train" remains an integral part of our vocabulary, seamlessly blending with our modern understanding of rail travel.