For readers who are unfamiliar with the Anglo-Welsh culture from which "Under Milk Wood" springs, I have made some notes. I hope they help:
The first five words of the narrator (“First Voice”) give a hint of the nature of what is to follow. It is an allusion to Lewis Carroll’s “Adventures of Alice in Wonderland” (“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.”) with which it shares a surreal dream-like quality.
“webfoot cocklewomen” – the South Wales coastline in which the play is set has a traditional cockle-picking industry, largely undertaken by women.
“Rhiannon” (pronounced rhee-ann-non) is a girl’s name popular mainly in Welsh-speaking parts of Wales and borrowed from the name of a goddess, queen or heroine of the mediaeval Celtic folk literature, “the Mabenogion.”
Milk Wood is reminiscent of the geography of Thomas’ chosen home town of Laugharne with its wooded “Sir John’s hill”, topped by Salt House Farm, stoops sharply to the sea (see Salt Lake Farm
“jolly, rodgered” The Jolly Roger (white skull and crossbones on black background is, of course, the flag flown by pirates, but here the comma and the spelling of “rodgered” makes clear that this is a sexual allusion (“rodger”, slang, to penetrate sexually).
“four-ale” public house, bar selling four different types of ale.
“Dai Bread” (Dai is pronounced like “die” and is a familiar contraction of “David”). It is a commonplace in Wales to give people nicknames based on their profession, to distinguish, one from the other, the many people with the same surnames (Jones, Davies, Roberts, Williams and Thomas being particularly prevalent).
“Bethesda” would be a common (Biblical) name given to a chapel of one of the several non-conformist free church denominations which abounded in Wales from the early 19th to the mid 20th centuries.
“com” is short for “combinations”, a sort of one-piece underwear favoured by the working classes in South Wales at the time.
“S.S Kidwelly” (SS= Steam Ship) Kidwelly is a village not far from Thomas birthplace and closer still to the home in Laugharne.
“Davy” (=Davy Jones’s locker) ie under the sea, therefore death by drowning. Also a reference to Sir Humphrey Davy, the inventor of the “Davy lamp” used by coal miners.
“Mumbles”, a little village at the other end of Swansea, a place where Thomas did much of his adolescent drinking.
“I never done what she said I never” A typical South Walian non-standard English expression for “I didn’t do it!”
“Lavabread” (more correctly spelt “laver-bread”) a foodstuff made of seaweed, very popular and made around the Swansea Bay area.
“snug” the comfortable room in a public house, a room in which the beer was more expensive, the chairs more comfortable and the swearing slightly less pervasive.
“tenors in Dowlais”. Concerts by male voice choirs were (and still are) a feature of the cultural life of the south wales coal mining valleys, where each coal pit would have its own male voice choir (and possibly also a brass band). Dowlais was one such village pit choir.
“Maesgwyn” village in Aberdare, a coal-mining town, about 10 miles from Dowlais.
“Samson-syrup-gold-maned” refers to the motif on the tins of Tate and Lyle syrup depicting Samson and the lion and the motto “out of the strong came forth sweetness”
“gooseberried” – “to play gooseberry” is to hang around when a couple are trying to get one another.
“big-besomed” – a besom is a primitive type of brush. This is a pun on “big-bosomed”.
“Myfanwy” stereotypical Welsh girl’s name, familiar to all steeped in Welsh culture as the subject of the lyrical poem and 19th century song of unrequited love. (pronounced meuh-van-wee)
“Ach y fi” (pronounced uch-ah-vee) (ch as in loch) A welsh expression of disgust.
“seventeen snoring gentle stone of Mister Waldo” (stone = 14 pounds
in weight)
“milk stout” a dark ale like Guinness.
“this little piggy…” a nursery song played through on an infant’s hand. (piggy = finger)
“what’ll the neighbours say”, a typical phrase from the tightly packed Bible-bashing judgemental communities of South Wales.
“chimbley”= chimney
“sennapods” a form of natural laxative.
“learn him” = teach him (a deviation from standard English common in Wales, because the Welsh word for ‘teach’ is the same as the Welsh word for ‘learn’.
“b.t.m” = bottom
“Blodwen” a Welsh girls’ name
“linoleum” a form of floor covering
“peke” = Pekinese breed of dog.
Eisteddfodau = Welsh competitive cultural festivals
Crwth (Welsh) = Welsh stringed instrument
Pibgorn (Welsh) = bagpipes
Parch (Welsh) = preacher
Gippo = slang expression for Gypsy (now considered offensive)
(Gypsies used to move from town to town calling at houses and offering clothes pegs for sale)
Cader Idris (pronounced Cadderr Eedriss) (=Seat of Arthur) mountain in North Wales.
Moel y Wyddfa (pronounced Moyl uh with-va) Summit of Snowdon (highest mountain in Wales)
Carnedd Llewelyn (pronounced Carr-neth LLay-well-in) a mountain in the Snowdon range (LL is a sound not found in English. It is created by placing one’s tongue on the palette and blowing air past it)
Plinlimmon = Five peaks in Cardiganshire West Wales.
Penmaen Mawr (pronounced Pen-mine-mow-r) ow as in ouch! Hill and village on North Wales Coastline
Sawdde (pronounced sow-thay) …. Nedd (pronounced Nay-th) all Welsh rivers.
Carreg Cennen (pronounced Carr-regg Kenn-nen) Hill with Castle atop in South Wales.
Goosegog = Gooseberry
Conk = large nose.
Baggage = term of abuse for woman without sense of decency.
“There’s a lovely morning”. A typical non-standard English expression meaning “this is a lovely morning”, arising from direct translation of equivalent Welsh expression.
“Boyo” South Walian expression for “Boy”.
“Aberystwyth” (pronounced Abb-err-ust-wi-th (th as in thick)) – seaside town in mid Wales. Also (here) hymn tune “Jesus Lover of My Soul”
Ty-pant (pronounced Tee-pant) Village on Welsh border.
Builth Wells = town in mid Wales.
Gorslas = town in West Wales
Twll (pronounced Too-LL) = Welsh “hole” (derogatory)
Cawl (pronounced cow-l) = Welsh “soup”
Pembroke City = a town in West Wales
Farthing = a unit of currency, one quarter of an old UK (pre-decimal) penny, therefore 1/960 of a £.
Fach = Welsh “small” (feminine form) and a term of endearment. The male form of the adjective is “bach” – so Thomas is playing on the composer’s name.