idyllically calm and peaceful; suggesting happy tranquility He now seemed to have entered on a halcyon period of life—congenial society, romantic and interesting surroundings. — Kennard, Nina H.

"calm, quiet, peaceful," 1540s, in halcyon dayes (translating Latin alcyonei dies, Greek alkyonides hemerai), 14 days of calm weather at the winter solstice, when a mythical bird (also ident [..]

adj. Calm.

 a bird. The Elizabethans believed that the halcyon had the power to calm the sea - hence the term "halcyon days".

Halcyon was a bird, now believed to have been the kingfisher. It was supposed to have a calming influence on the sea at the time of winter solstice. Folklore held that during the "halcyon days&qu [..]

(adj) marked by peace and prosperity(adj) idyllically calm and peaceful; suggesting happy tranquillity(n) (Greek mythology) a woman who was turned into a kingfisher(n) a large kingfisher widely distri [..]

genus|family|Alcedinidae|several tropical kingfishers

From the name of a genus of kingfisher birds, derived from Greek ἀλκυών (from the same source as Alcyone).