What does halcyon mean?

1. adjective: denoting a period of time idyllically happy, calm, and peaceful.

2. noun: A bird in Greek legend generally associated with the kingfisher. There was an ancient belief that the bird nested on the sea, which it calmed in order to lay its eggs on a floating nest.

According to Greek mythology, Alcyone, the daughter of the god of the winds, became so distraught when she learned that her husband had been killed in a shipwreck that she threw herself into the sea and was changed into a kingfisher. As a result, ancient Greeks called such birds alcyōn or halcyōn. The legend also says that such birds built floating nests on the sea, where they so charmed the wind god that he created a period of unusual calm that lasted until the birds' eggs hatched. This legend prompted people to use halcyon both as a noun naming a genus of kingfisher and as an adjective meaning either "of or relating to the kingfisher or its nesting period" or "calm."             --from Miriam Webster