NOUN (2)

1. (Greek mythology) 7 daughters of Atlas and half-sisters of the Hyades; placed among the stars to save them from the pursuit of Orion;

2. a star cluster in the constellation Taurus;

The Collaborative International Dictionary of English v.0.48:

Pleiades \Ple"ia*des\ (?; 277), n. pl. [L., fr. Gr. (?)]
   1. (Myth.) The seven daughters of Atlas and the nymph
      Pleione, fabled to have been made by Jupiter a
      constellation in the sky.
      [1913 Webster]

   2. (Astron.) A group of small stars in the neck of the
      constellation Taurus; -- called also the seven sisters.
      --Job xxxviii. 31.
      [1913 Webster]

   Note: Alcyone, the brightest of these, a star of the third
         magnitude, was considered by M[aum]dler the central
         point around which our universe is revolving, but such
         a notion has been thoroughly discounted by modern
         observations. Only six pleiads are distinctly visible
         to the naked eye, whence the ancients supposed that a
         sister had concealed herself out of shame for having
         loved a mortal, Sisyphus.
         [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

Pleiades
    n 1: (Greek mythology) 7 daughters of Atlas and half-sisters of
         the Hyades; placed among the stars to save them from the
         pursuit of Orion
    2: a star cluster in the constellation Taurus

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "Pleiades":
   Atlantides, Beehive, Cepheid variable, Hertzsprung-Russell diagram,
   Hyades, Messier catalog, NGC, Napaea, 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



Easton's 1897 Bible Dictionary:

Pleiades
   Heb. kimah, "a cluster" (Job 9:9; 38:31; Amos 5:8, A.V., "seven
   stars;" R.V., "Pleiades"), a name given to the cluster of stars
   seen in the shoulder of the constellation Taurus.