hal’shon. The name anciently given to the king-fisher, otherwise called alcedo; a bird that was said to lay her eggs in nests, on rocks near the sea, during the calm weather about the winter solstice. Hence,

Calm; quiet; peaceful; undisturbed; happy. Halcyon days were seven days before and as many after the winter solstice, when the weather was calm. Hence by halcyon days are now understood days of peace and tranquility.