This name for a body of water is Insular Celtic in origin and is applied to most lakes in Scotland and to many sea inlets in the west and north of Scotland. The word is Indo-European in origin; cf. Latin lacus. Lowland Scots orthography, like Scottish Gaelic, Welsh and Irish, represents with ch, so the word was borrowed with identical spelling. English borrowed the word separately from a number of loughs in the previous Cumbriclanguage areas of Northumbria and Cumbria. Earlier forms of English included the sound as gh. However, by the time Scotland and England joined under a single parliament, English had lost the sound. This form was therefore used when the English settled Ireland. The Scots convention of using ch remained, hence the modern Scottish English loch. In Welsh, what corresponds to lo is lu in Old Welsh and llw in Middle Welsh such as in today's Welsh placenamesLlanllwchaiarn, Llwchwr, Llyn Cwm Llwch, Amlwch, Maesllwch, the Goideliclo being taken into Scottish Gaelic by the gradual replacement of much Brittonic orthography with Goidelic orthography in Scotland. Many of the loughs in Northern England have also previously been called "meres" such as the Black Lough in Northumberland. However, reference to the latter as loughs, rather than as lakes, inlets and so on, is unusual. Some lochs in Southern Scotland have a Brythonic rather than Goidelic etymology, such as Loch Ryan where the Gaelic loch has replaced a Cumbric equivalent of Welsh llwch. The same is perhaps the case for water bodies in Northern England named with 'Low' or 'Lough' or otherwise it represents a borrowing of the Brythonic word into the Northumbrian dialect of Old English. Although there is no strict size definition, a small loch is often known as a lochan. Perhaps the most famous Scottish loch is Loch Ness, although there are other large examples such as Loch Awe, Loch Lomond and Loch Tay. Examples of sea lochs in Scotland include Loch Long, Loch Fyne, Loch Linnhe, and Loch Eriboll.
Uses of lochs
Some new reservoirs for hydroelectric schemes have been given names faithful to the names for natural bodies of water—for example, the Loch Sloy scheme, and Lochs Laggan and Treig. Other expanses are simply called reservoirs, e.g. Blackwater Reservoir above Kinlochleven.
Scottish lakes
Scotland has very few bodies of water called lakes. The Lake of Menteith, an Anglicisation of the Scots Laich o Menteith meaning a "low-lying bit of land in Menteith", is applied to the loch there because of the similarity of the sounds of the wordslaich and lake. Until the 19th century the body of water was known as the Loch of Menteith. The Lake of the Hirsel, Pressmennan Lake and Lake Louise are man-made bodies of water in Scotland known as lakes. The word "loch" is sometimes used as a shibboleth to identify natives of England, because the fricative sound is used in Scotland whereas most English people pronounce the word like "lock".