Halcyon
Adjective: calm, peaceful, tranquil, prosperous, happy, joyful, carefree
Noun: a mythical bird said to have the power of charming winds and waves into calmness
According to Greek mythology, Alkyone, 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 alkyon or halkyon. 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.
(Source: “Halcyon.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/halcyon. Accessed 13 Mar. 2021.)