The Collaborative International Dictionary of English v.0.48:

Hyades \Hy"a*des\, Hyads \Hy"ads\, n. pl. [L. Hyades, Gr. ?.]
   (Astron.)
   A cluster of five stars in the face of the constellation
   Taurus, supposed by the ancients to indicate the coming of
   rainy weather when they rose with the sun.
   [1913 Webster]

         Thro' scudding drifts the rainy Hyades
         Vext the dim sea.                        --Tennyson.
   [1913 Webster]