Records indicate that the name Turnbull came about when a Borders man saved Robert the Bruce by turning an angry bull which was set to gore the king. The king gave him the name Turnbull and gave him lands. There is also another story that the name comes from the old English "trumbald" meaning strong or bold.

The Turnbulls were a very turbulent family. John Turnbull was nicknamed "out-with sword" because of his fierce temper. On an opposite note, William Turnbull held a papal appointment in 1433, and that name appears as one of the conons of Glasgow Cathedral in 1452.