aoin-fheacht
Definitions (by source)
see feacht; i n-a., ‘at one time, together, simul,’ 1824, 10325; i n-a. riú, ‘along with them,’ 399; but a. amháin, ‘once, semel,’ 7817 (= aon-uair amháin, 2)
Trí Bior-Ghaoithe an Bháis: The Three Shafts of Death. Editor: Osborn Bergin.