noun

1. a legendary bird, identified with the kingfisher, which is supposed to have a peaceful, calming influence on the sea at the time of the winter solstice
2. Zool. any of a genus (Halcyon) of kingfishers of S Asia and Australia

Etymology: ME alcioun < L alcyon < Gr alkyōn, kingfisher, altered by folk etym. after Gr hals, sea

adjective

1. of the halcyon
2. tranquil, happy, idyllic, etc.: esp. in phr. halcyon days, usually with nostalgic reference to earlier times