This is a large region, from Co. Cork up to Co. Mayo, and was that in which Irish survived longest. As rule of thumb one can say that Irish receded from east to west. Furthermore, in this western and southern half of the country there is no survival of English from the first period with the possible exception of very small pockets in the major cities Cork, Limerick and Galway. Hence the English which developed here was that of the early modern period which arose through uncontrolled adult second language acquisition on the part of the rural inhabitants who represented the vast majority of speakers. Furthermore, the regional English input of the early modern period was of a largely West Midlands character.

The south and the west can also be distinguished from each other, at least on phonological grounds. The major segmental feature is the raising of /ε/ to /I/ before nasals in the south and southwest. This phenomenon is not spectacular in itself and is found in many varieties of English, most notably in the Lower South of the United States. But a consideration of the history of Irish English shows that this raising was of a more general type previously. If one looks at the many literary satires which contain Irish English, for instance in the collection by Alan Bliss (1979) or in A Corpus of Irish English (Hickey 2003), then one sees that formerly the raising occurred in non-nasal environments as well, e.g. divil, togithir, (from Dion Boucicault’s play Arragh na Pogue, 1864). What would appear to have happened in late 19^th-century and/or early 20^th-century Irish English is that the raising came to be restricted to environments in which it was phonetically natural, i.e. before nasals as these often trigger vowel raising due to their formant structure. This would mean that the situation in the south and south-west of Ireland (roughly the counties of Cork and Kerry) is a remnant of a much wider occurrence of /ε/ to /I/ raising.

A suprasegmental feature of the south, especially of the city of Cork, is the large intonational range characterised by a noticeable drop in pitch on stressed syllables.

This intonational pattern is shared by Cork Irish, in the remnants which are still extant, so that this prosodic feature can be viewed as an areal feature of the south/ south-west. The city of Cork also has a very open realization of the vowels in the LOT and THOUGHT lexical sets which is seen in (often stereotypical) pronunciations of the city’s name,  .

A distinctive feature of the west is the use of dental stops in the THINK-THIS lexical sets. In vernacular varieties in the east and south, alveolar stops are employed here. In the history of Irish English one can assume that Irish speakers switching to English would have used the nearest equivalent to English /θ, ð/ , i.e. the coronal stops of Irish. These stops were alveolar in the east and south, but dental in the west so that speakers used  as equivalents to the English dental fricatives in their second language English. This dental pronunciation of the west has become that of the supraregional variety of Irish English, itself deriving from usage in Dublin and spreading then throughout the country. But in vernacular Dublin English the realization of dental fricatives has been as alveolar stops so it is not clear how vernacular speakers in Dublin came to use dental stops. One view is that they picked this articulation up from the many immigrants into Dublin in the latter half of the 19^th century, because it (i) allowed them to dissociate themselves phonetically from vernacular speakers in the city and (ii) permitted a reversal of homophony in the words thinker and tinker.