literary a kingfisher

a mythical bird believed to breed at sea and calm the waves

calm; peaceful

the blue sky and halcyon sunshine of the genial spring weather — Charlotte Brontë

denoting a time, esp past, of idyllic tranquillity

Journalists arriving in Beirut would invariably be told of the halcyon days which had just ended, of the peaceful Phoenician land in which Christians and Muslims … could live in peace — Robert Fisk