The Collaborative International Dictionary of English v.0.48:

Hyades \Hyades\ n. (Greek mythology)
   The seven daughters of Atlas and half-sisters of the
   Pleiades; they nurtured the infant Dionysus and Zeus placed
   them among the stars as a reward.
   [WordNet 1.5] Hyades

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]

WordNet (r) 3.0 (2006):

Hyades
    n 1: (Greek mythology) 7 daughters of Atlas and half-sisters of
         the Pleiades; they nurtured the infant Dionysus and Zeus
         placed them among the stars as a reward

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "Hyades":
   Atlantides, Beehive, Cepheid variable, Hertzsprung-Russell diagram,
   Messier catalog, NGC, Napaea, Pleiades, Seven Sisters,
   absolute magnitude, binary star, black hole, double star, dryad,
   dwarf star, fixed star, flower nymph, giant star, glen nymph,
   globular cluster, gravity star, hamadryad, limoniad, magnitude,
   main sequence star, mass-luminosity law, mountain nymph,
   neutron star, nova, nymph, nymphet, nymphlin, open cluster, oread,
   populations, pulsar, quasar, quasi-stellar radio source,
   radio star, red giant star, relative magnitude, sky atlas,
   spectrum-luminosity diagram, star, star catalog, star chart,
   star cloud, star cluster, stellar magnitude, supernova, tree nymph,
   variable star, vila, white dwarf star, willi, wood nymph