Morphology: originally glan+nant+caeach
Phonetic: ll-anne-kai-ah-ch
Meaning "the banks of the Caeach brook ", this is the name of the famous Llancaiach Fawr Manor House, a living history attraction in the county borough. The area has been called Kayach 1536-9, Kaeach in the late 16th century and Lancayach in 1630. The river name may contain "caer" as a form of "cau" in the sense of "enclosing" as the area around Llancaeach Fawr and areas to the west are almost enclosed by the rivers Caeach and Bargod Taf. It was referred to as Lancaiach Vaur in 1795 in Church papers regarding the endorsement of "dissenting" places of worship (i.e. non-conformist as opposed to Church of England or Roman Catholic establishments).and Llancaiach appears on a map of Glamorganshire printed by Eyre and Spottiswoode of London in 1885.