Appendix:Old Irish s preterite verbs

The s preterite is the most common preterite class in Old Irish. All weak verbs of classes A I and AII as well as a few strong verbs take the s preterite. It goes back to the Proto-Indo-European sigmatic aorist found in Sanskrit (e.g. → ), Ancient Greek (e.g.  → ), Latin (e.g.  → ), Old Church Slavonic (e.g.  → ), Welsh (e.g.  →, ) and elsewhere.

In Proto-Celtic, the suffix must have contained geminate ss, since singleton s between two vowels became h in Brythonic and disappeared in Goidelic. This ss originated in the third-person singular, where the sequence *-s-t became *-ss by regular sound change; this ss then spread by paradigm leveling to the other forms.

The passive forms are not built with the s suffix; rather, they are derived from a verbal adjective with a suffix starting with t.

See Category:Old Irish s preterite verbs for a list of verbs belonging to this class.

Nondeponent endings
A sample verb for this class is, which ends in a broad consonant. The endings are as follows:

A sample verb ending in a slender consonant is :

Deponent endings
A sample verb for this class is. The conjunct endings are as follows (no absolute endings are attested for deponent verbs with a root ending in a broad consonant):

If the root ends in a consonant cluster, an epenthetic vowel is inserted between the cluster and a consonant-initial ending, as in :

Verbs ending in a slender consonant (including all those using the suffix ) are conjugated like :