Real Dictionary

Pleiades in American English
thethe seven daughters of Atlas and Pleione, placed by Zeus among the stars
plural noun: seven daughters of Atlas and half sisters of the Hyades, placed among the stars to save them from the pursuit of Orion. One of them (the Lost Pleiad) hides, either from grief or shame

Pleiades in British English 1
plural noun: the seven daughters of Atlas, placed as stars in the sky either to save them from the pursuit of Orion or, in another account, after they had killed themselves for grief over the death of their half-sisters the Hyades

Pleiades in British English 2
plural noun: a young conspicuous open star cluster approximately 370 light years away in the constellation Taurus, containing several thousand stars only six or seven of which are visible to the naked eye