Firth is the word in the Lowland Scots language and in English used to denote various coastal waters in Scotland and England. In mainland Scotland it is used to describe a large sea bay, or even a strait. In the Northern Isles it more usually refers to a smaller inlet. It is linguistically cognate to fjord (both from Proto-Germanic *ferþuz) which has a more constrained sense in English; a firth would most likely be called a fjord if it were situated in Scandinavia. Bodies of water named "firths" tend to be more common on the east coast, or in the southwest of the country, although the Firth of Lorn is an exception to this. The Highland coast contains numerous estuaries, straits, and inlets of a similar kind, but not called "firth" (e.g., the Minch and Loch Torridon); instead, these are often called sea lochs.

The ancient Greek historian Herodotus refers to firths repeatedly in his account of the Battle of Salamis in his 8th book of The Histories.

A firth is generally the result of ice age glaciation and is very often associated with a large river, where erosion caused by the tidal effects of incoming sea water passing upriver has widened the riverbed into an estuary. Demarcation can be rather vague. The Firth of Clyde is sometimes thought to include the estuary as far upriver as Dumbarton, but the Ordnance Survey map shows the change from river to firth occurring off Port Glasgow, while locally the change is held to be at the Tail of the Bank where the river crosses a sandbar off Greenock at the junction to the Gare Loch, or even further west at Gourock point.

However, some firths are exceptions. The Cromarty Firth on the east coast of Scotland, for example, resembles a large loch with only a relatively small outlet to the sea and the Solway Firth and the Moray Firth are more like extremely large bays. The Pentland Firth is a strait rather than a bay or an inlet.

Read more about Firth:  English Firths, Firths Outside Scottish Waters

Other articles related to "firth":

Firth, Shetland - History
... to the village, many abandoned croft houses still stand on the hill across Firth Voe from Mossbank ...
Clifton Firth - Photography
... Unlike Firth's typographical work, influenced by European Modernism, Firth's Photography was evocative of Hollywood glamour shots of the era ... Firth set up his photographic studio with his wife Patricia in 1938 ... The war years proved to be a lucrative period for Firth's photography, taking photos for those heading off to war, both of the soldiers for those they left behind, and of the ...
Canadian Ski Hall Of Fame - List of Inductees - F
... Douglas Firth, 1983* Sharon Firth, 1990 Shirley Firth, 1990 Nicolas Fontaine, 2007 Anna Fraser (-Sproule,) 1996 John Fripp, 1988 ...
... It is on the north shore of the Cromarty Firth, about 5 km north east of Dingwall, and 4 km south west of Evanton ... The Cromarty Bridge - carrying the A9 road - crosses the firth at Ardullie point ... passes by Ardullie, with the Far North Line running along the northern side of the firth ...
Clifton Firth
... Reginald Clifton Firth (1904–1980) was a New Zealand graphic designer and photographer ... especially the Swiss typographer Jan Tschichold, Firth’s design work of the late 1920s and early 30s was some of the earliest modernist graphic design in New Zealand ... Firth later went on to be a successful portrait photographer in Auckland during and after the Second World War ...