1. Masculine singular nouns


a. An adjective which modifies a nominative masculine singular common noun should be a basic form, neither lenited nor morphologically slenderised, nor altered in any other way.

For example:
  • Tha balach beag dubh anns an taigh. (There is a little dark-haired boy in the house) - balach (boy) is a masculine singular common noun, and is in the nominative case, since it is the subject of the verb tha (be); thus, the two adjectives which are modifiers of balach, i.e. beag (little) and dubh (black), must be basic forms, which have neither been lenited not slenderised. Compare with the following ungrammatical alternatives - *Tha balach bheag anns an taigh (lenited adjective), *Tha balach big anns an taigh (slenderised adjective), *Tha balach bhig anns an taigh (lenited, slenderised adjective).

b. An adjective which modifies a dative masculine singular common noun is, by default, also a basic form, neither lenited nor slenderised, not altered in any other way.

For example:
  • le balach beag dubh (with a little dark-haired boy) - balach (boy) is a masculine singular common noun, and is in the dative case, since it is the complement of the preposition le (with); thus, the two adjectives which are modifiers of balach, i.e. beag (little) and dubh (black), must be basic forms, which have neither been lenited not slenderised. Compare with the following ungrammatical alternatives - *le balach dhubh (lenited adjective), *le balach duibh (slenderised adjective), *le balach dhuibh (lenited, slenderised adjective).
  • bho thaigh mór gorm (from a big blue house) - taigh (house) is a masculine singular common noun, and is in the dative case, since it is the complement of the preposition bho (from); the noun also appears in its lenited form thaigh, since bho always lenites an immediately following noun; however, the two adjectives which are modifiers of thaigh, i.e. mór (big) and gorm (blue) are not lenited, but rather are basic forms - cf. *bho thaigh mhór ghorm.

c. However, an adjective which modifies a dative masculine singular common noun which is itself the complement+ of a definite article (or a definite variant preposition in -n) is always lenited, as long as the adjective itself does not start with a dental consonant (i.e. t-, d-, s-, l- or r-).

For example:
  • leis a' bhalach mhór dubh bhrònach (with the big sad dark-haired boy) - here the dative masculine singular common noun balach (boy) is the complement of the definite article a', and hence both it and the two adjectives which modify it and which do not begin with a dental consonant, i.e. mór (big) and brònach (sad), are lenited; however, the adjective dubh (black) is not lenited, since d- is a dental consonant.
  • bhon t-seann duine mhór snog (from the big nice old man) - the dative masculine singular common noun duine (man) is the complement of the prenominal adjective seann (old), which is itself the complement of the definite variant preposition bhon (from the); the effect of bhon is to lenite every following non-dental noun or adjective (i.e. mhór), and to prefix t- to an immediately following word beginning with s-; the adjective snog (nice) starts with a dental s- and hence is left unlenited.

Note that lenition of the adjective in this case is actually a property of the leniting an form of the definite article, rather than of the noun itself. The leniting nature of the former overrides the non-leniting nature of the latter.

d. An adjective which modifies a genitive masculine singular common noun should be both lenited and slenderised (even if the genitive form of the noun is not formed by slenderisation).

For example:
  • ainm balaich mhóir dhuibh (a big dark-haired boy's name) - the (slenderised) masculine singular common noun balaich (of a boy) is in the genitive case, since it is a modifier? of the common noun ainm (name); thus the two adjectives which modify the noun, mór (big) and dubh (black), are both lenited and slenderised.

Note that an adjective which modifies a genitive masculine singular noun is both lenited and slenderised even in cases where the genitive singular form of the noun is not formed by lenition and slenderisation.

For example:
  • ainm an locha bhig ghoirm (the little blue lake's name) - here the genitive singular form of the masculine noun loch (lake) is not formed by slenderisation, but rather by adding -a on the end; in any case, the modifying adjectives beag (little) and gorm (blue) need to be both lenited and slenderised.

e. Summary for adjectives modifying masculine singular common nouns:

singular

masculine

indefinite
definite
nominative
-
dative
-
lenited*
genitive
lenited, slenderised

And with examples:

singular

masculine

indefinite
definite
nominative
balach beag dubh
am balach beag dubh
dative
balach beag dubh
a' bhalach bheag dubh
genitive
balaich bhig dhuibh
a' bhalaich bhig dhuibh

2. Feminine singular nouns


a. An adjective which modifies a nominative feminine singular common noun should be a lenited, morphologically non-slenderised form.

For example:
  • Tha caileag mhór dhubh anns an taigh. (There is a big dark-haired girl in the house) - caileag (girl) is a feminine singular common noun, and is in the nominative case, since it is the subject of the verb tha (be); thus, the two adjectives which are modifiers of caileag, i.e. mór (big) and dubh (black), must be lenited, non-slenderised forms. Compare with the following ungrammatical alternatives - *Tha caileag mór anns an taigh (non-lenited adjective), *Tha caileag mhóir anns an taigh (slenderised adjective).

b. An adjective which modifies a dative feminine singular common noun should be a lenited, slenderised form.

For example:
  • le caileig mhóir dhuibh (with a big dark-haired girl) - caileig (girl) is a feminine singular common noun, and is in the dative case, since it is the complement of the preposition le (with) and has thus been slenderised; the two adjectives which are modifiers of caileig, i.e. mór (big) and dubh (black), hence must be both lenited and slenderised. Compare with the following ungrammatical alternatives - *le caileig dhubh (non-slenderised adjective), *le caileig duibh (non-lenited adjective), *le caileig dubh (non-lenited, non-slenderised adjective).

c. However, in informal Gaelic, where morphological slenderisation of dative feminine singular common nouns is typically relaxed, adjectives are generally also not slenderised, just like in the nominative.

For example:
  • le caileag mhór dhubh is an informal version of the formal Gaelic le caileig mhóir dhuibh (with a big dark-haired girl).

d. An adjective which modifies a genitive feminine singular common noun should slenderised, with an -e appended on the end, but not lenited.

For example:
  • ainm caileige móire duibhe (a big dark-haired girl's name) - the (slenderised, -e suffixed) masculine singular common noun caileige (of a girl) is in the genitive case, since it is a modifier? of the common noun ainm (name); thus the two adjectives which modify the noun, mór (big) and dubh (black), are both slenderised and -e suffixed, but not lenited.

Note that an adjective which modifies a genitive feminine singular common noun is both slenderised and -e suffixed even in cases where the genitive singular form of the noun is not formed in this way.

For example:
  • ainm na sùla bige goirme (the little blue eye's name) - here the genitive singular form of the feminine noun sùil (eye) is not formed by slenderisation and -e suffixation, but rather by deslenderisation and -a suffixation; in any case, the modifying adjectives beag (little) and gorm (blue) need to be both slenderised and -e suffixed.

e. However, in informal Gaelic, adjectives which modify feminine genitive singular common nouns are generally just lenited basic forms, just like in the nominative.

For example:
  • ainm caileige mhór dhubh is an informal version of the formal Gaelic ainm caileige móire duibhe (a big dark-haired girl's name).

f. Summary for adjectives modifying feminine singular common nouns:

singular

feminine
nominative
lenited
dative
lenited, slenderised
genitive
slenderised, -e

And with examples:

singular

feminine

indefinite
definite
nominative
caileag bheag dhubh
a' chaileig bheag dhubh
dative
caileig bhig dhuibh
a' chaileig bhig dhuibh
genitive
caileige bige duibhe
na caileige bige duibhe

3. Plural nouns


a. A monosyllabic adjective which modifies a plural noun has an unstressed vowel added onto the end. If the adjective ends with a broad consonant, then this is -a. If the adjective ends with a slender consonant, then this is -e.

For example:
  • taighean beaga gorma (little blue houses).
  • caileagan òga glice (clever young girls).

b. On the other hand, an adjective whose basic form consists of more than one syllable, and which is a modifier of a plural noun, does not have a suffix added.

For example:
  • caileagan brònach beaga (sad little girls).
  • taighean beaga inntinneach (interesting little houses).

c. An adjective which modifies a plural noun which has been formed by slenderisation should be lenited.

For example:
  • balaich bheaga mhilis (sweet little boys) - .
  • caoraich fhliucha mharbha (dead wet sheep) - .

d. On the other hand, an adjective which modifies a plural noun which has been formed in some other way should not be lenited.

For example:
  • taighean beaga milis (sweet little houses) - .
  • bà fliucha marbha (dead wet cows) - .

e. Summary for adjectives modifying plural common nouns:

plural

-an
slenderised
monosyllabic
-a/-e
-a/-e, lenited
polysyllabic
-
lenited

And with examples:

plural

-an
slenderised
monosyllabic
caileagan beaga
balaich bheaga
polysyllabic
caileagan milis
balaich mhilis

[MM: What about specific genitive forms of nouns, e.g. nam balach b(h)eaga?]

4. Summary of adjective declension


[table]



List of monosyllabic adjectives:

Non-dental-lenitable:

àrd
bàn
beag
blàth
bochd - poor
ceàrr
cruaidh
fliuch
fuar
geal
gearr - short
geur - sharp
glan
glic
goirt
gorm
marbh
math
mìn
mòr
òg
olc - bad
sgìth
ùr

Dental lenitable:

daor
dearg
deas
doirbh - difficult
dona - bad
donn - brown-haired
dubh
luagh
snog
teann
teth - hot
tinn
tiugh - thick
trom

beairteach
bòidheach - pretty
brèagha - beautiful
brònach
buidhe - yellow
dìleas - loyal
domhainn - deep
duilich - hard
fada - long
furasda - easy
gaolach - loving
goirid - short
inntinneach - interesting
ìseal - low
làidir
milis - sweet
modhail
toilichte - happy
uasal - noble