Morphology: ynys+du
Phonetic: uh-niss-thee
Developed as a small model settlement in the 1820s by J.H. Moggridge and best known as the birthplace and home of the poet Islwyn (the Reverend William Thomas (1832-1878), a Calvinistic Methodist minister). As with Hafodyrynys, though "ynys" usually refers to an island in the sea, it can also refer to an area of land between two rivers or a meadow near a river. Literally meaning "black river meadow", the name derives from the fact that the area was surrounded by coal mines and slag heaps and that the river often would run black with coal dust.