docoissin

From dí- +‎ com- + Proto-Celtic *sesone, the preterite of *sannati ultimately from Proto-Indo-European *senh₂- (“to reach, attain”), before it was conflated with *swannati (“to play an instrument”).^[1]

do·coissin

1. to be, exist
   • c. 800, Würzburg Glosses on the Pauline Epistles, published in Thesaurus Palaeohibernicus (reprinted 1987, Dublin Institute for Advanced Studies), edited and with translations by Whitley Stokes and John Strachan, vol. I, pp. 499–712, Wb. 21^a13

     .i. do·beir inso arnab uilib cumac[h]tib di·choissin i nim et talam.

     He puts this for all the powers which exist in heaven and earth.

   • c. 800–825, Diarmait, Milan Glosses on the Psalms, published in Thesaurus Palaeohibernicus (reprinted 1987, Dublin Institute for Advanced Studies), edited and with translations by Whitley Stokes and John Strachan, vol. I, pp. 7–483, Ml. 108^c14

     .i. singulis uirtutibus Dei .i. as la Dia cech rann neirt du·choissin, amal ata les inna nert.

     i.e. singulis virtutibus Dei, i.e. that every part of virtue [might?] that there is belongs to God, as the virtues [might?] belong to him.

This verb is almost always used in relative clauses in the form "X that exist(s)".

The verb is severely defective; only the 3rd-person singular deuterotonic present form exists. Any non-third-person subjects must be expressed via infixed Class A object pronouns.

• díxnigidir

• Gregory Toner, Sharon Arbuthnot, Máire Ní Mhaonaigh, Marie-Luise Theuerkauf, Dagmar Wodtko, editors (2019), “do-coissin”, in eDIL: Electronic Dictionary of the Irish Language