The Collaborative International Dictionary of English v.0.48:

Dale \Dale\ (d[=a]l), n. [AS. d[ae]l; akin to LG., D., Sw.,
   Dan., OS., & Goth. dal, Icel. dalr, OHG. tal, G. thal, and
   perh. to Gr. qo`los a rotunda, Skr. dh[=a]ra depth. Cf.
   Dell.]
   1. A low place between hills; a vale or valley.
      [1913 Webster]

            Where mountaines rise, umbrageous dales descend.
                                                  --Thomson.
      [1913 Webster]

   2. A trough or spout to carry off water, as from a pump.
      --Knight.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dale
    n 1: an open river valley (in a hilly area)