town, Blaenau Gwent county borough, historic county of Monmouthshire (Sir Fynwy), Wales, in the valley of the River Ebbw. Coal mining was its main economic interest from about 1850 until the last mines closed in the 1980s. Nantyglo, to the north, was the site of famous ironworks. Some light manufacturing has been introduced to Abertillery since the 1930s, mostly with government assistance, and the town is a commercial centre. Pop. (2001) 11,887.