abergavenny - Abergavenny (Rom. Gobannium); abergavenny - Municipal borough and market town of Monmouthshire, England. It lies on the river Usk, where the Gavenny joins it, and is 23 m. S. of Hereford, on the L.M.S. and G. W. rlys. It has an old grammar school, the remains of the castle of the Nevilles, and a parish church that was formerly a Benedictine priory. The town suffered severely during the border fighting of the 12th arid 13th centuries, being burnt by Owen Glendower (q.v.) in 1404. Market days, Tues. and Fri. Pop. 8,608.