—adj.
1 calm, peaceful (halcyon days).
2 (of a period) happy, prosperous.
—n.
1 any kingfisher of the genus Halcyon, native to Europe, Africa, and Australasia, with brightly-coloured plumage.
2 Mythol. a bird thought in antiquity to breed in a nest floating at sea at the winter solstice, charming the wind and waves into calm.
Etymology: ME f. L (h)alcyon f. Gk (h)alkuon kingfisher
Useful english dictionary. 2012.