Type Word Usage Old Irish Meaning & History Old Irish word meaning "battle, fight, feud" [1]. Related ItemsDetails Given Name DescendantsFiacre(French) Fiachra(Irish) Fiachra, Fiachrae(Irish Mythology) Fiachrae(Old Irish) Sources & References Matasović, Ranko. Etymological Dictionary of Proto-Celtic. Brill, 2009, page 421.