Trefkenon 1254, Trefkeno c.1291, Trefgenan 1331-2, Tresgenan 1338, Treffgenon 1365-6, Trefgenon 1393-4, 1549, Tregonon 1507, 1606-7, Tregynnon 1547, ll.dref gynon c.1566, Tregonen 1583, Tregynon 1583, c1679, Tref gynon 1550-1600

Welsh tref and personal name Cynon. 'settlement of man called) Cynon'. The church dedication has been ascribed to Cynon but there is no early evidence for this. ====== Any connection between Cynidr and Cynon and Tregynon seems to occur first in an ode by Lewys Dwnn to David Lloyd Blayney, High Sheriff, 1577====== Tregynon was also one of the three swyddi or ringildries of Cedewain recorded as comot Conan (for Cwmwd Cynon) 1584.