Quote:
Perhaps someone would like to give the Munster and standard versions in separate threads? (marked "(GM)" and "(CO)" respectively, please.
I'll give the Munster version a try (expect an error/omission or two

).
The situation in Munster is a bit more complex that it is (or seems to be, at least) in Ulster and Connacht with variation in the various sub-dialects.
Eclipsis is the norm.
In
Corca Dhuibhne it's almost always the case, e.g.
sa mbaile, don dtalamh etc.
In
Muscraighe lenition follows
den, don and
sa(n) (
t is prefixed to
s - this is actually a form of lenition, not eclipsis) with the exception of
f which is eclipsed, e.g.
den ghort, sa tseomra, den bhfeirm.
In
Rinn Ua gCuanach (a) only
c and
p are lenited, following a preposition and article which forms a single syllable (including
aige (
ag) which is generally pronounced
'ge'n and
roimh(e) pronounced
roimhe'n "rine" or "royn"), e.g.
don ngort but
don pháirc,
ón mbuachaill but
ón chailín, (b) words beginning with
s are treated as if in the nominative case, i.e.
t prefixed if feminine, none if masculine, e.g.
sa seomra, sa tsráid, (c)
d and
t are normally not eclipsed, e.g.
ar an talamh.
There will, of course, be further variations in other areas (e.g.
f is sometimes lenited after
san, den &
don).
aige falla --------- aige'n bhfalla --------- aiges na fallaí
ar chlo(i)ch ------------ ar an gclo(i)ch --------- ar na clocha
as bosca ---------------- as an mbosca --------- as na boscaí
chuig: chun (/chuin/chún) is usual, followed by genitive.
de chlár ---------------- den chlár/den gclár (den usually pronounced don) --------- des na cláracha
do chara -------------- don chara/don gcara --------- dos na cairde
fara bosca-------------- fairis an mbosca --------- fairis na boscaí
fé chlo(i)ch -------------- fén gclo(i)ch/fén chlo(i)ch ---------- fés na clocha
fá/fó : not used in Munster. Um is the equivalent.
i mbosca ------------- sa' bhosca/ sa' mbosca (san earrach, sa bhfóghmhar/san fhóghmhar) --------- sna boscaí
ionsar : not used in Munster.
le (/lé) cara -------------- leis an gcara --------- leis na cairde
ó cheanntar ------------ ón gceanntar/ ón cheanntar --------- ós na gceanntair
roimh (/roim/roimis/roimhe) chlo(i)ch ------------- roimis an gclo(i)ch/roimhe'n chlo(i)ch --------- roimis na/roimhes na clocha (roimh in standard Irish)
trí fhuinneo(i)g ------------ tríd/trís an bhfuinneo(i)g --------- trís na fuinneoga
thar chlo(i)ch ----------------- thar an gclo(i)ch --------- thar na clocha
um (/uim) chlo(i)ch----------------- um an gclo(i)ch --------- um na clocha
go cathair ----------- go dtí'n chathair, go dtís na cathracha (go can't be directly followed by the article, if you need the article you use go dtí before it and the noun in is the nominative so feminine nouns are lenited) (and go prefixes h to vowels, go hÉirinn, go hAlbain).
The old dative plural survives to a very limited extent, e.g.
ar na clochaibh,
leis na cairdibh etc.
P.S. (The following is not limited to Munster) There is a difference in meaning between lenited and unlenited forms of some words directly following
ar and
thar (and some other prepositions??), e.g.
ar bhord = "on a table" but
ar bord = "on board" (phrase),
ar mhuin chapaill = "on a horse's back" but
ar muin chapaill = "on horse-back",
thar mhuir = "over a sea" but
thar muir = "overseas" etc.