fosisedar

Old Irish

From fo- +‎ Proto-Celtic *sistati; the same stem is found in ar·sissedar and do·airissedar.

fo·sisedar (prototonic ·fuisedar, verbal noun fóesam or foísitiu)

to confess, acknowledge, admit
- 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. 132^a1
  Fo·sissetar a pect[h]u ind firien ⁊ as·berat is airi ro·uctha in doiri: fo bith a pec[thae].
  The righteous confess their sins and say that it is for this [reason] that they have been brought into captivity: because of their sins.
to profess, avow
to guarantee, become responsible for
- c. 700–800 Táin Bó Cúailnge, published in Táin Bó Cúailnge. Recension I (1976, Dublin: Dublin Institute for Advanced Studies), edited and with translations by Cecile O'Rahilly, TBC-I 3872
  Guitir dál ó Chonchobar do Ailill co turcbáil n-gréné arabárach, ⁊ ba·sisestar Ailill ar feraib hÉrend ⁊ ar in longess, ⁊ ba·sisestar Conchobar ar Ultaib.
  He asked Ailill for a truce until sunrise the next day, and Ailill guaranteed it on behalf of the men of [all of] Ireland and the exiled Ulstermen while Conchobar guaranteed it for the Ulstermen.

The verb's two different verbal nouns are not interchangeable. Each is used depending on the semantics.

The senses "confess, acknowledge, admit" and "profess" have the verbal noun uses the verbal noun foísitiu.
The senses relating to guarantees, protection, etc. use fóesam.

Mutation of *fosisedar*
radical	lenition	nasalization
fo·sisedar	fo·ṡisedar	unchanged

Note: Certain mutated forms of some words can never occur in Old Irish.
All possible mutated forms are displayed for convenience.