Alternative Name: Rhymni
Morphology: from the word “rhwmp”
Phonetic: r-hum-knee
An industrial village that grew up around the Rhymney Ironworks – the Union Ironworks Co. in 1803, with the village and Ironworks taking their name from the river. The name was chosen as the parish name in 1843 and also gave its name to the former district council that served the area from 1974 to 1996. The name of the river appears in 1101 as Remni and goes through a number of changes over the years – Rumeya 1274, Rompney 1314, Rempny 1340. In 1479 the bridge was recorded as pontem Remeebrygge and as Pont Remny / Remney Bridge in 1536-39. The river rises from a point above a former farm called Blaenrhymni and flows through the valley, leaving Caerphilly county borough after Machen and eventually reaching the sea at Rempney haven or creke as it was shown in 1565, what is today known as Rumney / Tredelerch in Cardiff. Given the many spellings of the name that includes the letter "p", in all likelihood the name derives from an old Welsh word "rhwmp" meaning "auger" or "gimlet", thus meaning "a river which bores like an auger" to describe how the river has bored or carved its way through the valley.