This name derives from the Irish Gaelic “ceallach > ceallaigh”, meaning “one who suffers strife during battle, war, strife, bright-headed, from brilliant mind”. The element “ceall” probably comes from the Gaelic, meaning "church", with the addition of a diminutive suffix. According to other interpretations it means "bright", or comes from the word “ceallach” "war", meaning "warrior". In both cases, the etymology is probably also shared by the name Ceallach. Saint Kilian, also spelled Killian (Irish: Cillian), was an Irish missionary bishop and the apostle of Franconia (nowadays the northern part of Bavaria), where he began his labors towards the end of the 7th century.