Appendix:Old Irish verbs

Old Irish has a very complex conjugation system, marked by extensive allomorphy in combination with two sets of verb endings (absolute and conjunct) depending on the verb's position in the sentence. For a complete discussion, see.

Like many ancient Indo-European languages, Old Irish has a number of deponent verbs, which had a distinct set of endings, but these tended to be replaced by the regular nondeponent forms in Old Irish and especially over the course of Middle Irish. The modern Goidelic languages no longer have distinct deponent forms.

Old Irish verbs normally have four stems, which are used to form nine tense/mood combinations, each of which can be take either deponent or nondeponent endings.
 * Present stem
 * Present indicative
 * Imperfect indicative
 * Imperative
 * Future stem
 * Future
 * Conditional
 * Preterite stem
 * Preterite active
 * Perfect active
 * Subjunctive stem
 * Present subjunctive
 * Past subjunctive

There are also three nonfinite forms:
 * Verbal noun
 * Past participle
 * Verbal of necessity

and the preterite passive form, etymologically related to the past participle.

Present stems
The Old Irish present stem is used to form:
 * the present indicative
 * the imperfect indicative
 * the imperative

Under Thurneysen's analysis, there are eight present stem classes, divided into two groups, weak (A) and strong (B).


 * Weak (the third-person singular conjunct nondeponent form ends in a vowel):
 * A I
 * A II
 * A III
 * Strong (the third-person singular conjunct nondeponent form ends in a consonant):
 * B I
 * B II
 * B III
 * B IV
 * B V

Other authors classify the present stems differently. Strachan's system is as follows:
 * Strong:
 * A 1 (= Thurneysen's B I and B III)
 * A 2 (= Thurneysen's B IV and B V)
 * A 3 (= Thurneysen's B II)
 * Weak:
 * B 1 (= Thurneysen's A I)
 * B 2 (= Thurneysen's A II)

McCone divides the classes into three groups:
 * Strong:
 * S1 (= Thurneysen's B I and B III)
 * S2 (= Thurneysen's B II)
 * S3 (= Thurneysen's B IV and B V)
 * Weak:
 * W1 (= Thurneysen's A I)
 * W2 (= Thurneysen's A II)
 * Hiatus (all = Thurneysen's A III)
 * H1
 * H2
 * H3

Future stems

 * f future
 * s future
 * a future
 * é future
 * i future

Preterite stems

 * s preterite
 * t preterite
 * suffixless preterite
 * reduplicated s preterite

Subjunctive stems

 * a subjunctive
 * s subjunctive
 * e subjunctive