 The origins of its name are not known for certain but "ynys" is Welsh for a river-meadow (i.e., an "island" – the main meaning of "ynys" – in otherwise marshier ground beside a river) and Forgan is a mutation of the name Morgan; a reasonable translation of the name would therefore be Morgan's Meadow.The River Tawe flows past Ynysforgan so it is not unreasonable to speculate that it is the river in question.Several other nearby locations also use the term Ynys in their names including Ynystawe (the neighbouring village to Ynysforgan), Ynystanglws Farm (near Ynystawe), and Ynysmeudwy (near Pontardawe).