Cader Idris. Cadair Idris or Cader Idris is a mountain in Gwynedd, Wales, which lies at the southern end of the Snowdonia National Park near the town of Dolgellau.
   The peak, which is one of the most popular in Wales for walkers and hikers, is composed largely of Ordovician igneous rocks, with classic glacial erosion features such as cwms, moraines, striated rocks, and roches moutonnées. Cadair Idris means Idris's Chair.
   Idris is usually taken to be the name of a giant or, alternatively, it may refer to Idris ap Gwyddno, a 7th-century prince of Meirionnydd who won a battle against the Irish on the mountain. Idris ap Gwyddno was in fact referred to as Idris Gawr in some mediaeval genealogies of Meirionydd.
   The basic meaning of the word cadair is seat, chair. In place names cadair can mean stronghold, fort, fortress or mountain or hill shaped like a chair.
   The spelling cader represents a spoken variant of the standard form cadair. It appears that Cadair/Cadeir Idris is the form used in the earliest Welsh-language sources. In a poem in his own hand in the second half of the 15th century, the poet Lewys Glyn Cothi wrote Dros gadair idris gedy. Around 1600, John Jones of Gellilyfdy referred to y mynydh neu bhan neu bhoel a elwir Cadeir Idris'. The spoken form represented by cader had developed by the end of the Middle Ages and as a result the form Cader Idris was often used in English and Latin d
Wikipedia ...