Cumbrian dialect or Cumberland dialect is a local dialect of Northern England in decline, spoken in Cumberland, Westmorland and Lancashire North of the Sands. Some parts of Cumbria have a more North-East English sound to them. Whilst clearly spoken with a Northern English accent, the Cumbrian dialect shares much vocabulary with Scots. A Cumbrian Dictionary of Dialect, Tradition and Folklore by William Rollinson exists, as well as a more contemporary and lighthearted Cumbrian Dictionary and Phrase Book.

As with other English dialects north of the Humber–Lune Line and the closely related Scots language, Cumbrian is descended from Northern Middle English and in turn Northumbrian Old English. Old English was introduced to Cumbria from Northumbria, where it was initially spoken alongside the native Cumbric language.

Despite the modern county being created only in 1974 from the counties of Cumberland, Westmorland and north Lancashire and parts of Yorkshire, Cumbria is an ancient division. Before the arrival of the Romans, the area was the home of the Carvetii tribe, which was later assimilated to the larger Brigantes tribe. These people would have spoken Brythonic, which developed into Old Welsh, but around the 5th century AD, when Cumbria was the centre of the kingdom of Rheged, the language spoken in northern England and southern Scotland from Lancashire and Yorkshire to Strathclyde had developed into a dialect of Brythonic known as Cumbric (the scarcity of linguistic evidence, however, means that Cumbric's distinctness from Old Welsh is more deduced than proven). Remnants of Brythonic and Cumbric are most often seen in place names, in elements such as caer 'fort' as in Carlisle, pen 'hill' as in Penrith, glinn 'valley' and redïn 'ferns, bracken' as in Glenridding, and craig 'crag, rock' as in High Crag.

The most well known Celtic element in Cumbrian dialect is the sheep counting numerals which are still used in various forms by shepherds throughout the area, and apparently for knitting. The word 'Yan' (meaning 'one'), for example, is prevalent throughout Cumbria and is still often used, especially by non-speakers of 'received pronunciation' and children, e.g. "That yan owr there," or "Can I have yan of those?"

The Northern subject rule may be attributable to Celtic Influence.

Before the 8th century AD Cumbria was annexed to English Northumbria and Old English began to be spoken in parts, although evidence suggests Cumbric survived in central regions in some form until the 11th century.

A far stronger influence on the modern dialect was Old Norse, spoken by Norse and/or Norse-Gael settlers who probably arrived on the coasts of Cumbria in the 10th century via Ireland and the Isle of Man. Many Cumbrian place names in or near coastal areas are of Norse origin, including Ulverston from Ulfrs tun ('Ulfr's farmstead'), Kendal from Kent dalr ('valley of the River Kent') and Elterwater from eltr vatn ('swan lake'). Many of the traditional dialect words are also remnants of Norse influence, including beck (bekkr, 'stream'), laik (leik, 'to play'), lowp (hlaupa, 'to jump') and glisky (gliskr, 'shimmering').

Once Cumbrians had assimilated to speaking Northumbrian English, there were few further influences on the dialect. In the Middle Ages, much of Cumbria frequently swapped hands between England and Scotland but this had little effect on the language used. In the nineteenth century miners from Cornwall and Wales began relocating to Cumbria to take advantage of the work offered by new iron ore, copper and wadd mines but whilst they seem to have affected some local accents (notably Barrow-in-Furness) they don't seem to have contributed much to the vocabulary.