Pleiades

[plee-uh-deez, plahy-] /ˈpli əˌdiz, ˈplaɪ-/
plural noun
1.
Classical Mythology. 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.
2.
Astronomy. a conspicuous group or cluster of stars in the constellation Taurus, commonly spoken of as seven, though only six are visible.
Origin
1350-1400; Middle English Pliades < Latin Plīades < Greek Pleíades (singular Pleías); akin to pleîn to sail

Pleiad

[plee-uh d, plahy-uh d] /ˈpli əd, ˈplaɪ əd/
noun
1.
any of the Pleiades.
2.
French Pléiade
[pley-yad] /pleɪˈyad/ (Show IPA). a group of seven French poets of the latter half of the 16th century.
3.
(usually lowercase) any group of eminent or brilliant persons or things, especially when seven in number.
British Dictionary definitions for Pleiades

Pleiades1

/ˈplaɪəˌdiːz/
plural noun
1.
(Greek myth) 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

Pleiades2

/ˈplaɪəˌdiːz/
plural noun
1.
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 Compare Hyades1

pleiad

/ˈplaɪəd/
noun
1.
a brilliant or talented group, esp one with seven members
Word Origin
C16: originally French Pléiade, name given by Pierre de Ronsard to himself and six other poets after a group of Alexandrian Greek poets who were called this after the Pleiades1

Pleiad

/ˈplaɪəd/
noun
1.
one of the Pleiades (stars or daughters of Atlas)
Word Origin and History for Pleiades
n.

late 14c., the seven daughters of Atlas and Pleione, transformed by Zeus into seven stars, from Latin Pleiades, from Greek Pleiades, perhaps literally "constellation of the doves" from a shortened form of peleiades, plural of peleias "dove" (from PIE root *pel- "dark-colored, gray"). Or perhaps from plein "to sail," because the season of navigation begins with their heliacal rising.

Old English had the name from Latin as Pliade. Mentioned by Hesiod (pre-700 B.C.E.), only six now are visible to most people; on a clear night a good eye can see nine (in 1579, well before the invention of the telescope, the German astronomer Michael Moestlin (1550-1631) correctly drew 11 Pleiades stars); telescopes reveal at least 500. Hence French pleiade, used for a meeting or grouping of seven persons.

Pleiades in Science
Pleiades
  (plē'ə-dēz')   
A loose collection of several hundred stars in the constellation Taurus, at least six of which are visible to the unaided eye.
Pleiades in the Bible

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.