a river of Ireland, which, rising in the Bog of Allen, near Carbery in Co. Kildare, and flowing in a north-easterly direction, passes Trim, Navan and Drogheda, and enters the Irish Sea, 4 m. below the town last named. It is navigable for barges to Navan, 19 m. from its mouth. Much of the scenery on its banks is beautiful, though never grand. About 2 m. west of Drogheda, an obelisk, i 50 ft. in height, marks the spot where the forces of William III. gained a celebrated victory over those of James II., on the 1st of July' 1690, known as the battle of the Boyne.