Penrith, a municipality of Cumberland county, New South Wales, Australia, on the Nepean River, 34 m. by rail W. by N. of Sydney. Penrith and the adjoining township of St Mary's are chiefly remarkable for their connexion with the railway. The iron tubular bridge which carries the line over the Nepean is the best of its kind in the colony, while the viaduct over Knapsack Gulley is the most remarkable erection of its kind in Australia. There are large engineering works and railway fitting shops at Penrith, which is also the junction for all the western goods traffic. The inhabitants of both towns are mainly railway employes. Pop. (1901), of Penrith 3539, of St Mary's 1840.