Alternative spellings of Cadmarch are Camarch or Cadfarch and the river Cammarch that flows through the village is the most likely source of the place-name. Tysilio is associated with the church by the twelfth-century poet Cynddelw Brydydd Mawr, and in the Breton Life of Tysilio.

Wade-Evans gives Cynog as the original patron. Huw Thomas states that Cynog was nicknamed Cynog Camarch, 'that is the Dispised Kynog', a reference to 'his cheerful forbearance' that was resented by his fellow monks before they killed him. The connection with Cynog is additionally drawn from the date of the parish wake, 8 October, which is also the usual date for the feast of Cynog.