The derivation of the term can be found in Old Irish as a marked instant, a breath made definite.

It is defined as the smallest practical measure of time in Inis Fíor. Used when something needs a short count — a brief wait at a gate, the steeping of herbs, the cooling of metal, the span of a short rite. A nóiméad carries the sense of a moment given edges, time made deliberately small.

You will find it in the singular as Nóiméad and in the plural as Na Nóiméid.