What's a declension?

In Irish, a declension is basically a group of nouns that tend to form the plural and genitive according to a common pattern. (Declensions are more complex in some languages.)

Why do I care what declension a noun belongs to?

Knowing the declension can help you figure out the genitive and plural form of the noun.

What declensions are there?

The first declension is almost all male nouns. The second is mostly female. The third and fourth declensions have both male and female nouns. Technically, there are 5 declensions. However, the fifth declension is sort of miscellaneous, and it's full of common nouns you probably already know, so I think it's easier to ignore it.

How do I tell what declension a noun is?

Look at the common (nominative) form of the noun and ask yourself the questions in the diagram below. Be sure to stop at the first "yes" answer, because that's the declension that the noun probably belongs to.

Note: An abstract noun represents something that you can't see, touch, feel, taste or smell.

noun declensions



Examples

leabhar

fuinneog

iontráil

páiste

airde

Exceptions

There are exceptions, of course, so it is best to learn the declension when you learn the noun, or to check the dictionary. Here is one important exception to know: im and sliabh are m2 (most second-declension nouns are feminine, but these are masculine).

I know the declension, now what do I do?

Once you've figured out which declension a noun belongs to, a chart like the one below will help you remember how the noun declines. I recommend that you read a good explanation of noun declensions, while keeping this diagram handy.

There's a lot of information packed into this diagram, and it can be a bit overwhelming at first. In the beginning, just pay attention to the first one or two nouns in each declension; they represent the most common patterns.

Remember, for strong plural gpl = npl = vpl


ns gs vs npl gpl vpl
m1
ending in a broad consonant
bád
fear
béal
íasc
síol
bacach
taoiseach
gaiscíoch
báid
fír
béil
éisc
síl
bacaigh
taoisigh
gaiscigh

= gs = gs = ns Add -a to ns
deireadh
saol
deiridh
saoil
deirí
saolta
deirí = npl
f2
ending in a slender consonant, or -eog, -óg, -lann
beach
bos
scornach
eaglais
beiche
boise
scorn
eaglaise
= ns beacha
bosa
scornacha
eaglaisí
= ns = npl
aisling = npl
aislinge aislingí
m3
ending in -aeir, -éir, -eoir, -óir, -úir
cainteoir
gnólacht
tincéir
am
bainteora
gnólachta
tincéara
ama
= ns cainteorí
gnólachtaí
tincéirí
amanna
= npl = npl
f3
ending in -áint, -úint, -irt
>1 syllable ending in -cht
adhmáil
beannacht
ban-aba
canúint
droim
admhála
beannachta
ban-aba
canúna
drama
= ns admhálacha
beannachtaí
ban-abaí
canúintí
dromanna
= npl = npl
m4
ending in -ín or a vowel
bata
ciste
cailín
run
rí
bus
= ns = ns bat
cistí
cailíní
runaithe
rithe
busanna
= npl = npl
ordú
cruinn
orduithe
cruinnithe
orduíthe
cruinnithe
f4
abstract nouns ending in -e or í
bearna
féile
= ns = ns bearn
féilte
= npl = npl
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