Caibidil a Ceathair Déag: 

Initial Mutations (na hAthruithe Tosaigh)

Eclipsis (an tUrú)

Eclipsis (griech.:omission, disappearance) is the substitution of the unvoiced consonants with the corresponding voiced ones (c becomes g, f becomes bh, t becomes d, p becomes b).
Voiced consonants are then replaced with nasals (b becomes m, d becomes n, g becomes ng). This is why eclipsis is sometimes called nasalisation.

Here is some background about the causes of eclipsis.

about the written notation of eclipsis:

consonant eclipsed spoken consonant eclipsed spoken
b mb  [m] g ng [ng]
c gc [g] p bp [b]
d nd [n] t dt [d]
f bhf [v] / [w]      

l, m, n, r, s
(andh, j, v, w, z)
no eclipsis


d, t are (except in Munster) not eclipsed after a preposition + article! e.g.:ar an teach = on the house
s can is some dialects in Munster "be eclipsed". There, the unvoiced [s] is replaced with the voiced s [z], a sound which is otherwise foreign to Irish. This remains unnoted in written Irish. (e.g.: an sagart [@ sag@rt], ar an sagart [er' @ zag@rt])


  1. after the prepositions ag, ar, as, le, mar, ó, faoi, roimh, thrí, thar, um if with the article an: (in Munster always, in Connacht by d, t no eclipsis as well as a t-prefix preceding s by femin. nouns) e.g.:  ar an mbord = on the table
  2. after a preposition with an article sa (in Connacht always, in Munster only by f, in the standard/Ulster, lenition):
    e.g.: sa bhfarraige = in the sea
  3. after the preposition i  if without article  e.g. i dteach = in a house
    (similarly also after the archaic prepositions go = with, iar = to )
  4. after the genitive plural article na  e.g. na dtithe = of the houses
  5. after the plural possessive pronouns   ár, bhur, a e.g. ár dteach = our house, a gcarr = their car
  6. after the numbers 7-10, (17-19, 27-29 etc.) e.g.: deich dteach = ten houses
  7. verb after verbal particles / conjunctions   an, go, nach, mura, dá, sula, ach a
  8. verb after the interrogative (in the meaning "where")
  9. verb after the indirect relative particle a
  10. verb after the generealising relative pronoun a ("all, that ")
    as well as after the expression diabhal a ( = ní,  "not", lit.: "devil all, that ")
  11. after the prefix éa- ( = "un-") Here, one leaves out the sound being eclipsed (éa- + cóir = éagóir = injustice, éa + trom = éadrom = not heavy, light )
  12. in a few place names after those nouns which are normally things, e.g. Loch nEachach (Lough Neagh), as well as after other nouns in the genitive plural, e.g. Mainistir Ó dTorna (Abbeydorney), lit.: "Abbey of the O'Dorneys"

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initial mutations
lenition, n-, t-, h-, d'-prefix
Gramadach na Gaeilge
© Lars Braesicke 1999 / 2000

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