A river of Scotland, formed by the junction of Duchray Water and the Avondhu, streams which rise one on Ben Lomond and the other on Ben Venue, and which, after 14 and 9 m., unite at Aberfoyle; the river thence flows with many windings, called Links, through some of the fairest country of the eastern lowlands to Alloa (51½ m.), where begins the Firth, which stretches 51 m. to the German Ocean, and which at Queensferry is spanned by a massive railway bridge known as the Forth Bridge (1882-1890).