Caer (Old Welsh: cair or kair) is a placename element meaning a fortification, a camp, an inclosure, a wall or mound of defence,[7] while Cynwrig in Old Welsh means high hill.

[3] Originally Twmpath Castle was a Welsh camp called Caer Cynwrig, which was captured and occupied by the Normans and became the third largest motte in the Lordship of Glamorgan.

[3] Cadw has described the monument as being of "National importance for its potential to enhance our knowledge of medieval defensive practices.

[3] It retains significant archaeological potential, with a strong probability of the presence of both structural evidence and intact associated deposits.

[3] Legend has it that it is a burial mound erected about 1089 for Iestyn ap Gwrgan, Lord of Glamorgan.