Vocabulary is the other area in which dialect differences are apparent. Most learners are quickly taught that gan (N.W.) -- "with" -- and gyda (S.W.) are one and the same, and that gan requires conjugating. This is an important and common vocabulary difference for students to recognize. Usually, because of its ease, the South Welsh form is taught; indeed, many learners are concentrated in South Wales, so there is a tendency to teach those word forms although alternatives are always given. Some other word differences which I frequently encounter are nawr (S.W.)/rwan (N.W.) -- "now;" moyn (S.W.)/eisiau (N.W.) -- "to want;" dere (S.W.)/tyrd (N.W.) -- "come!;" and mam-gu (S.W.)/nain (N.W.) -- "grandmother."
Fortunately, despite varying pronunciation and the short list of words that differ between North and South Wales, the two dialects are mutually intelligible and don't differ in structure. Some of the more localized, older forms of dialects differ even more in terms of pronunciation, though they are still understandable. Gwentian, for example, is characterized by a lot of reductions--parts of syllables get dropped or shortened, such as gwbod instead of gwybod - "to know." Modern South Welsh shares some of these characteristics.
In my opinion, dialects add richness, depth, and liveliness to a language. As a serious learner, it is exciting to expand my vocabulary and understanding to include the various forms of Welsh. For anyone else who might be interested in learning more about dialects in Wales, please consult the sources below. Many thanks to the members of the Welsh-L mailing list who helped me round up several book titles.
Websites:
Gwales.com. (An Internet inquiry and ordering service for Welsh and Welsh-interest books, courtesy of the Welsh Books Council.)
Gwentian Index on Gwefan Cymru-Catalonia. (A description, glossary, and bibliography.)
Gwybodiadur. (has a nice list of books and resources of all kinds.)
University of Wales Press. (Not only do they publish many interesting titles, if you click on "Site Links," you'll find links to numerous Welsh-interest publishing sites and booksellers.)
Books For Learners:
King, Gareth. Colloquial Welsh. London and New York: Routledge Ltd, 1995. (p. 195 and p. 210)
Rhys Jones, T.J. Teach Yourself Welsh. Chicago: NTC Publishing Group, 1992. (p. 274-276)
Scholarly Books:
Fynes-Clinton, O. H. The Welsh Vocabulary of the Bangor District. London: Oxford University Press, 1913. Re-issued by Llanerch Publishers (Lampeter), 1995.
Griffiths, Bruce. Gwerin-Eiriau Maldwyn. Gwasg Gee, 1981.
Jones, John (Myrddin Fardd). Gwerin-eiriau Sir Gaernarfon, Ei Hystyr a'u Hanes. Nodiadau gan Bruce Griffiths. Llangefni: Llygad yr Haul, 1979 [1907].
