Plurals shmurals and how to predict them

Ok, this is definitely work in progress but someone asked for this so I'll have a go.

First off, to quote Captain Barbosa, these are more like guidelines, plurals in most languages are hard to predict with certainty but there are some things that can make like easier. Also note that many words can take more than one plural form, depending on the (native) speaker.

Anyone starts talking at you about first declension, second declension etc, nod politely and - unless you are aiming for a degree in historical linguistics - run. Though technically useful, working off the basis of these old categories requires in-depth knowledge of Old Irish... see what I mean?

Irregular nouns are just that, irregular, so you need to learn those. The ones you should learn off as soon as possible are: Alba, athair, bean, bó, bràthair, brù, cù, deoch, Dia, druim, duine, Éirinn, fear, fuil, leabaidh, mac, muir, piuthar, sgian, taigh, talamh. There's lots more, but they will do for starters.

Best bets

Your best bets are special endings (in the singular) which take fixed plurals.

-ach

With a masculine noun ending in -ach, the plural normally is -aich:

• balach » balaich
• boireannach » boireannaich

Watch out, some masculine nouns like cladach change to cladaichean. Not only that, you must really watch out for gender because those ending in -ach which are feminine take a different plural, for example làrach » làraichean. On the bright side, that's also fairly regular so if you know the gender, you can fairly safely go for -aichean is the noun is feminine:

• làrach » làraichean
• gruagach » gruagaichean

-(e)achd

Ignoring the issue of gender for the moment... ok fine, not ignoring the issue of gender. The rule of thumb is, words which end in -(e)achd which are one syllable long (e.g. achd, smachd...) tend to be masculine. Those which are two or more syllables long, are virtually all feminine (e.g. mòrachd, Gàidhealtachd...).

On the bright side, they all take -an as their plural:

• achd » achdan
• feachd » feachdan
• éifeachd » éifeachdan

-(e)adh and -idh

These are nice. They're virtually all masculine and virtually all take -(a)idhean as a plural if the word consists of noun + adh (meaning that they must have two syllables at least):

• atharrachadh » atharrachaidhean
• moladh » molaidhean

Irrespective of their gender (though most are masculine) words ending in -idh also behave like that:

• ainmhidh » ainmhidhean
• aghaidh » aighaidhean
• bàillidh » bàillidhean

-(e)ag

If you have a feminine noun with the diminutive ending -(e)ag, then the plural will always be -an:

• caileag » caileagan
• marag » maragan
• cuileag » cuileagan

Careful, there are some masculine nouns which look like they have -(e)ag at the end, in particular aiseag. Usually, the plural is still -(e)an (» aiseagan) but the other cases will obviously be different, e.g. an t-aisgeag.

-eal

Also fairly predictably, words ending in -eal add -an for the plural:

• caisteal » caistealan
• inneal » innealan

As usual, there are exceptions, most notably perhaps aingeal which changes to ainglean.

-air/-(e)adair/-(a)iche/-(e)ar

These are agentive endings. Bits that you stick onto another noun to show that someone makes or does something, like -er in English which gives you fish » fisher, wash » washer, clean » cleaner and so on. The plural of these is almost invariably -(e)an:

• iasg » iasgair » iasgairean
• clach » clachair » clachairean
• saighdear » saighdearan
• cluich » cluicheadair » cluicheadairean
• mara » maraiche » maraichean

Careful, this only works if the noun is made up of a noun plus an ending. There are some feminine nouns which aren't "composed" like that which behave differently. As a rule of thumb, if you take the ending away and what you're left with doesn't make sense, then it's not one of these. For example, cathair and nathair, if you take the -air away, leave you with cath and nath and that just doesn't make sense, i.e. nath doesn't mean anything on it's own so it's not nath+air but just one word like that. See the next section for those.

-air and -ir

If the -air at the end is not the doer/maker ending, then the noun is usually feminine and syncopates its plural. I'll explain that some other time in detail, in short it means that you lose a syllable so the plural is -thraichean:

• nathair » nathraichean
• màthair » màthraichean
• acair » acraichean
• litir » litraichean

-(e)an

If you have a masculine noun ending in the diminutive ending -(e)an, then plurals are normally restricted to either -ain/-ein or -an. It's hard to predict which but if in doubt, you're usually better going with -an. Type 1

• balachan » balachain
• corran » corrain
• cuman » cumain

Type 2

• cuilean » cuileanan
• ballan » ballanan

-(e)as

These are nice. They almost all take -an as the plural:

• solas » solasan
• carthannas » carthannasan

The fly in the ointment is doras which is usually dorsan in the plural.

-th

There's a ... tendency let's say for words ending in -th to have -an as a plural:

• guth » guthan
• gath » gathan
• gaoth » gaothan

Bùth can take bùthan as the plural but bùithtean is more common.

Being exclusive

If the noun in question is sipping Singapore Sling, you need to step away from the screen, take a deep breath and do something else for a while. Ok ok. What I meant to say is that some plurals can be excluded on the basis of gender. For example, almost all nouns which slenderise for plural (e.g. balach » balaich, bòrd » bùird) are masculine. So if you have a noun and you're pretty sure it's feminine, then in almost all cases you must stick an ending on to show the plural.

Loans

A lot of loanwords go for -(a)ichean in the plural:

• càr » càraichean
• bàr » bàraichean
• clas » clasaichean

Short and sweet

The other "pointer" is that nouns which do something really bizarre to the vowel (like bòrd » bùird) are a) all masculine and b) only one syllable long. So a word like òran cannot have a plural that looks like ùirean or something like that. It's kinda obvious once you've realized this but it can help you cut down the number of options.

• ceann » cinn
• cat » cait
• fiadh » féidh
• ball » buill