 One interpretation of the placename is that it means 'green river' as in the Welsh river named Irfon.It has had many variants, such as Irwyn (1322), Ervin (1259) Irewin (1429–30), Irrvin (1528), and Irwin (1537).Another author lists Yrewin, c.1140; Irvin, c.1230; Orewin, c.1295, with a meaning of 'west flowing river.'