The Collaborative International Dictionary of English v.0.48:

Adown \A*down"\, prep.
   Down. [Archaic & Poetic]
   [1913 Webster]

         Her hair adown her shoulders loosely lay displayed.
                                                  --Prior.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Adown \A*down"\, adv. [OE. adun, adoun, adune. AS. of d[=u]ne
   off the hill. See Down.]
   From a higher to a lower situation; downward; down, to or on
   the ground. [Archaic] "Thrice did she sink adown." --Spenser.
   [1913 Webster]