The Old Irish a subjunctive, which is the most widespread and productive subjunctive conjugation, is found with both weak and strong verbs. The endings are almost exactly the same as in the class A I presents, with a few exceptions as indicated below.
A sample verb for this class is marbaid(“to kill”). In the present subjunctive, the endings are the same as in the A I present indicative except for the first- and second-person singular. The past subjunctive endings are identical to the imperfect indicative endings of class A I:
Present subjunctive
1st sg.
2nd sg.
3rd sg.
1st pl.
2nd pl.
3rd pl.
Passive singular
Passive plural
Absolute
marba
marbae
marbaid
marbmai
marbthae
marbait
marbthair
marbtair
Conjunct
·marb†
·marbae
·marba
·marbam
·marbaid
·marbat
·marbthar
·marbtar
Relative
marbas
marbmae
marbtae
marbthar
marbtar
†In class B II verbs, the first-person singular conjunct is also attested with a slender final consonant, e.g. gaibid has both ·gab and ·gaib in the first-person singular present subjunctive.
Past subjunctive
1st sg.
2nd sg.
3rd sg.
1st pl.
2nd pl.
3rd pl.
Passive singular
Passive plural
·marbainn
·marbtha
·marbad
·marbmais
·marbthae
·marbtais
·marbthae
·marbtais
In class A II verbs, the endings are the same, but the final consonant of the root is slender (palatalized), which has an effect on the spelling. An example is léicid(“to leave”):
Present subjunctive
1st sg.
2nd sg.
3rd sg.
1st pl.
2nd pl.
3rd pl.
Passive singular
Passive plural
Absolute
léicea
léice
léicid
léicmi
léicthe
léicit
léicthir
léictir
Conjunct
·léic
·léice
·léicea
·léicem
·léicid
·léicet
·léicther
·léicter
Relative
léices
léicme
léicte
léicther
léicter
Past subjunctive
1st sg.
2nd sg.
3rd sg.
1st pl.
2nd pl.
3rd pl.
Passive singular
Passive plural
·léicinn
·léicthea
·léiced
·léicmis
·léicthe
·léictis
·léicthe
·léictis
In class B IV, the n of the present indicative stem is absent in the subjunctive, and the endings are added directly to the vowel that ends the root. In the case of vowel-initial endings, the two vowels merge in some cases. As this is a rather small class, many forms are unattested. An example is crenaid(“to buy”); the forms marked with * below are not attested, but are likely to have been the forms.
A sample verb for this class is labraithir(“to speak”). The endings are the same as in the class A I present indicative except for the first person singular forms of the present subjunctive:
Present subjunctive
1st sg.
2nd sg.
3rd sg.
1st pl.
2nd pl.
3rd pl.
Passive singular
Passive plural
Absolute
labrar
labraither
labraithir
labraimmir
labraithe
labraitir
labraithir
labraitir
Conjunct
·labrar
·labraither
·labrathar
·labrammar
·labraid
·labratar
·labrathar
·labratar
Relative
labrathar
labrammar
labratar
labrathar
labratar
Past subjunctive
1st sg.
2nd sg.
3rd sg.
1st pl.
2nd pl.
3rd pl.
Passive singular
Passive plural
·labrainn
·labratha
·labrad
·labraimmis
·labraithe
·labraitis
·labraithe
·labraitis
Here too, the stem of A II verbs ends in a slender consonant, which affects the spelling:
