In the direction of, and moving with, the wind.
Birds fly swiftly down the wind.
(obsolete) Decaying; declining.
Source: en.wiktionary.orgIn Arcady there lies a crystal spring Ring'd all about with green melodious reeds Swaying seal'd music up and down the wind. Here on its time-defaced pedestal The image of a half-forgotten God Crumbles to its complete oblivion. Eleanor Farjeon
She's so many women, He can't find the one who was his friend. So he's hanging on to half her heart. He can't have the restless part, So he tells her to hasten down the wind. Warren Zevon