Maerdy is a village and community in the county borough of Rhondda Cynon Taf, and within the historic county boundaries of Glamorgan, Wales, lying at the head of the Rhondda Fach Valley. "Maerdy" is a Welsh word meaning "house of the slaves, and may indicate a medieval origin. The "maer" was usually appointed by the king; the maer biswail was …Maerdy is a village and community in the county borough of Rhondda Cynon Taf, and within the historic county boundaries of Glamorgan, Wales, lying at the head of the Rhondda Fach Valley. "Maerdy" is a Welsh word meaning "house of the slaves, and may indicate a medieval origin. The "maer" was usually appointed by the king; the maer biswail was not as important and wielded less authority than the "maer". "Maerdy" was also used for a 'summer dwelling' as well as for a 'dairy farm'. The name is found in several locations throughout Wales. 'Mardy' represents the local Gwentian dialect form of the written "maerdy".