feas, feasadh
Definitions (by source)
[V. 20] pret. pass. of defective verb -feadar was known 2080.
Duanaire Mhéig Uidhir: The poembook of Cú Chonnacht Mág Uidhir, Lord of Fermanagh 1566-1589. Editor: David Greene. Translator: David Greene.
in phr. ní feas dóibh, they do not know.
Stories from Keating's History of Ireland. Editor: Osborn Bergin.