Halcyon means calm, peaceful, idyllic, prosperous, carefree or joyful.
The word comes from the greek myth of Alcyone and Ceyx. These two were happily together and seemingly in love. So much so that they treacherously called each other “Zeus” and “Hera”. Apparently Zeus didn’t like this very much.
Ceyx went to sea to consult an oracle, despite Alcyone’s pleading him to stay. Zeus used the opportunity to demonstrate his displeasure and cast a storm at Ceyx’s ship, apparently knocking it clear into the heavens with a thunderbolt. Ceyx drowned and Morpheus, god of dreams, appeared to Alcyone to tell her of her lover’s fate.
In her despair, Alcyone went to the shore and threw herself into the sea. But before she could hit the water, she turned into a bird – Halcyon, the kingfisher. Ceyx then came back to life as a kingfisher and they coasted above the surface into the sunset…
The Halcyon Days became the 14 days over the winter solstice when Alcyone’s father, Aeolus, the god of winds, would calm the usually tempestuous weather so his lovely kingfisher daughter could lay eggs and nest without danger.
So Halcyon came to mean a streak of good fortune or a lucky break amidst adversity, as the 14 days of calm weather would be considered amid a stormy winter. Over the years it has morphed to more generally mean a peaceful time or the good old days.