The surname Traynum is believed to have originated in England during the medieval period. It is thought to be derived from an Old English word meaning "three streams" or "three brooks," likely referring to a geographical feature or location where the name first arose.

One of the earliest recorded instances of the name Traynum can be found in the Domesday Book of 1086, which was a comprehensive survey of landowners and properties in England commissioned by William the Conqueror. This suggests that the name had already been established by the late 11th century.

During the Middle Ages, the name Traynum was primarily concentrated in the counties of Gloucestershire and Wiltshire in southwestern England. It is possible that the name was initially associated with a specific place or manor bearing a similar name, such as Traynum Manor or Traynum Village, though records of such locations are scarce.

In the 14th century, a notable figure named John Traynum was mentioned in the rolls of the Exchequer, the government department responsible for collecting taxes and managing royal revenues. This John Traynum was a landowner and taxpayer in the county of Gloucestershire, indicating the continued presence of the name in that region.

By the 16th century, the Traynum surname had spread to other parts of England, including the counties of Somerset and Dorset. During this time, a family of Traynums resided in the town of Sherborne, Dorset, where they were involved in local affairs and held positions of prominence within the community.

One of the most notable individuals bearing the Traynum name was Sir Richard Traynum (1562-1643), a wealthy merchant and alderman in the city of Bristol. He was known for his philanthropy and contributed significantly to the development of the city's infrastructure, including the construction of public buildings and the improvement of trade routes.

In the 17th century, the Traynum surname also found its way to the American colonies, with several families settling in the New England region. One such individual was William Traynum (1625-1692), who arrived in Massachusetts Bay Colony in 1638 and later became a prominent landowner and farmer in the town of Ipswich.

Throughout the 18th and 19th centuries, the Traynum name continued to be present in various parts of England, as well as in the United States and other English-speaking countries. Notable figures during this period included Robert Traynum (1745-1821), a British naval officer who served in the Royal Navy during the American Revolutionary War, and Mary Traynum (1802-1887), an American educator and advocate for women's rights in the state of New York.