The River Tay (Scottish Gaelic: Tatha, IPA: [ˈt̪ʰa.ə]; probably from the conjectured Brythonic Tausa, possibly meaning 'silent one' or 'strong one' or, simply, 'flowing') is the longest river in Scotland and the seventh-longest in Great Britain. The Tay originates in western Scotland on the slopes of Ben Lui (Scottish Gaelic: Beinn Laoigh), then flows easterly across the Highlands, through Loch Dochart, Loch Iubhair and Loch Tay, then continues east through Strathtay (see Strath), in the centre of Scotland, then southeasterly through Perth, where it becomes tidal, to its mouth at the Firth of Tay, south of Dundee. It is the largest river in the British Isles by measured discharge. Its catchment is approximately 2,000 square miles (5,200 square kilometres), the Tweed's is 1,500 sq mi (3,900