​ABERCARN, an urban district in the southern parliamentary division of Monmouthshire, England, 10 m. N.W. of Newport by the Great Western railway. Pop. (1901) 12,607. There are collieries, ironworks and tinplate works in the district; the town, which lies in the middle portion of the Ebbw valley, being situated on the south-eastern flank of the great mining region of Glamorganshire and Monmouthshire.