soirnéis

Etymology
. Apparently attested only in 's work Eochair-Sgiath an Aifrinn (literally, ‘Buckler of the Mass’, i.e. an explanatory defense of the Roman Catholic Mass, written ca. 1615), where the phrase appears twice on p. 114 of the edition edited by Patrick O’Brien and published in 1898.

Noun

 * 1)  furnace

Inflection
No inflected forms are attested, but assuming it was declined exactly like, the following forms would be expected: