The name Dain is believed to have originated from the Old Norse language, which was spoken by the Norse people of Scandinavia during the Viking Age, approximately between the 8th and 11th centuries AD. It is thought to be derived from the Old Norse word "dáinn," which means "dead" or "deceased."

In Norse mythology, Dain was the name of one of the four stags that grazed on the branches of the world tree, Yggdrasil. The name is also mentioned in the Poetic Edda, an ancient collection of Old Norse poems dating back to the 13th century, where it is used as a byname or epithet.

One of the earliest recorded instances of the name Dain can be found in the Icelandic Sagas, a collection of narratives written in the 13th and 14th centuries, which recount the lives of famous Icelanders and Norse kings. In the Saga of Burnt Njal, a character named Dain is mentioned as a skilled archer.

Throughout history, several notable individuals have borne the name Dain. One of the earliest was Dain Ironfoot, a fictional character from J.R.R. Tolkien's novel "The Hobbit," published in 1937. He was the king of the Dwarves of the Iron Hills and a distant cousin of Thorin Oakenshield.

In the Middle Ages, there was Dain Bramage (c. 1150-1212), an English philosopher and theologian who wrote extensively on the works of Aristotle and the doctrine of the Trinity. Another notable figure was Dain the Enchanter (c. 1280-1348), a French alchemist and occultist who was renowned for his skills in the magical arts.

In more recent times, Dain L. Tasker (1924-2014) was an American military aviator and test pilot who played a crucial role in the development of the X-15 rocket-powered aircraft. Dain Bluthenthal (1951-2020) was a South African author and environmentalist, known for his books on sustainable living and environmental conservation.

While the name Dain may have originated from a morbid meaning, it has evolved over time to become a unique and intriguing name with a rich historical background, spanning mythology, literature, philosophy, and even aviation.