The term Orcadian is sometimes used in English but the dialect is known as Orkney in Scots.

Today's Orkney dialect, like that of Shetland, is pervaded with Norse words and turns of speech. Orkney dialect differs from Shetland in that Shetland follows Nordic stress patterns whereas Orkney has a rising intonation akin to Welsh or Irish. There are dialectical differences, particularly in pronunciation and vocabulary, throughout the islands, though the main distinction in accent is that between the mainland of Orkney and the north islands

Characteristics

Today's Orkney dialect, like that of Shetland, is pervaded with Norse words and turns of speech. Orkney dialect differs from Shetland in that Shetland follows Nordic stress patterns whereas Orkney has a rising intonation akin to Welsh or Irish. There are dialectical differences, particularly in pronunciation and vocabulary, throughout the islands, though the main distinction in accent is that between the mainland of Orkney and the north islands. Some of the main distinct features of Orkney dialect are:

The use of the verb 'to be' as an auxiliary in place of English 'to have', e.g.

I'm just meed the tea (I have just made tea).

The use of the verb 'to be' as a future tense main verb, e.g.

I'll just be (I will just be with you/ I am just coming/ I will just be there).

Usage of a plural for a singular noun, e.g

This feet is sair but the ither feet is fine (This foot is sore but the other foot is fine).

The second person singular pronoun thoo is still used in a familiar sense, e.g.

Whit dis thoo mak o that? (What do you make of that?).

Tak thee tea (Take your tea).

Compound prepositions at the end of a sentence, e.g.

I'm gan oot a luk upbye (I am going out for a look about up the road).

Prepositions generally at the end of a sentence, e.g

Whar's me breeks at? (Where are my trousers?).

And finally, something which harks back straight to Old Norse - whar means both 'who' and 'where', e.g.

Whar's that? (Who's that?/Where's that?).

In Orkney name is neem, table is teeble and able is eeble. In some parts, such as North Ronaldsay (North Ronalshee), a hard k often softens to a soft ch so How are you keeping? becomes Hoo are thoo cheepin? All over Orkney j and g usually become ch in speech so that German jam is pronounced Cherman Cham. Whereas in Shetland du (you) is used, in Orkney this changes to thoo. Thee is also used in the islands. In Scots generally where words end in -it (-ed in English), the Orcadian takes the form -id, so general Scots lockit (locked) and biggit (built) become lockid and biggid.

A good example of Orcadian used for a formal discourse is the lecture given by JT Smith Leask in 1906 before the Glasgow Orkney and Shetland Literary and Scientific Association.  The following extract illustrates well the characteristics of Orcadian pronunciation and vocabulary:

Trou da hairst dat wanjoy Secretary o wirs Tamson speered me gin I wadna gae a paper I wir ain dialec.  I teltim at aince at I hed been sae lang awa fae hame at feinty bit o me minded on ony od, an even gin I deud I hed tent da way o makin a dacent discourse.  Da common galloos wadna leed tae me, bit jeust pat me doon for id.  Tae mak a lang story short, he sent a lang screed back tae me sayin I high English Thure a leer.  Noo, bairns, I pit id tae yersels, waas dat right?  I wad hae taen da laa api im for takin awa me guid name I dat wey gin gin id warna at a body kens laaweers ar sic scoondrels dey wad hae jeust reuined is baith, sae I made ap me mind hid wad be better tae geong aboot wi a little wirt name nor loss da twa tree babees I hae

History

For almost a thousand years the language of the Orkney Islands was a variant of Norse known as Norroena (or Norn in Scots). The distinctive and culturally unique qualities of the Orkney dialect spoken in the islands today derive from this sister language of Faroese, which too developed from Norse brought in by settlers in the 9th century, and from Icelandic. 

Direct Scots influence on Orkney really began from the 1330's when the earldom passed into the hands of Malise earl of Strathearn. Norn was steadily eroded as a language of governance and the pledging of Orkney to Scotland as part of the dowry of Margaret of Denmark in 1468 merely accelerated the process. 

Records in Scots began to appear in Orkney from the 1430s onwards and there are very few documents written in Norwegian left.. There are indications that Orkney began developing its own dialect of Scots from an early period.  For example John Ben, who lived in the islands in 1529, wrote a description in which he stated that they (Orcadians) use a peculiar idiomatic expression, as when we say Guid day,Guidman, they say goand da, boundae, etc.  In 1701 the Reverend John Brand also commented of the Orcadians that though their language was generally the same as the north of Scotland yet several of the Isles have some Words and Phrases peculiar to themselves.   

Scots became the language of governance and Norwegian disappeared very quickly, remaining in the Orkney dialect of today as specific words and grammatical features. The first real study of the dialect was Edmonstons An Etymological Glossary of the Shetland and Orkney Dialect published in 1866. 

Region

The capital of the islands is Kirkwall (Kirkwal), while other notable places include Stromness (Strumniz) and the islands of Rousay (Rousee), Stronsay (Stronsee) and Westray (Westree). Orkney has a rich farming and fishing tradition along with a traditional knit ware industry. Orkney dialect is used throughout Orkney in every situation. Radio Orkney features dialect, there is teaching of dialect in schools and in Orkney College, while writers publish in Orkney dialect. There is also a research centre based at Orkney College which deals with language.   
Writers in the dialect include Christina McKay Costie, Walter Traill Dennisonand David Towrie. Those with an interest in the dialect may wish to consultThe Orkney Dictionary by Margaret Flaws and Gregor Lamb (Kirkwall, 1996).