[Ir. feidlech, enduring, constant].
Shadowy but historical king of Tara, best remembered as the father of many celebrated daughters, including Medb (whose mother may have been Cruacha), Clothra, Eithne (5), Éle, and Mugain. Among the sons attributed to him are Furbaide (1) and the Three Finns of Emain Macha, known collectively as Finn Emna, who rose against him with the encouragement of Conchobar mac Nessa; although they knocked Eochaid unconscious, they were defeated. The battle is remembered in the place name Drom Chrioch [ridge of the heart cry], coextensive with Drumcree, Co. Westmeath. Eochaid Feidlech was the brother of Ailill Anglonnach and Eochaid Airem, with whom he is often confused. In Togail Bruidne Da Derga [The Destruction of Da Derga's Hostel], he is married to the beautiful Étaín (1), taking, the place of Eochaid Airem, as in Tochmarc Étaíne [The Wooing of Étaín]; the child of this union is Étaín Óg.Tuathal Techtmar, one of the most important of pre-Christian kings, claimed direct descent from Eochaid Feidlech through six generations.