What is "hyads"

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.

Thro' scudding drifts the rainy Hyades Vext the dim sea.
--Tennyson.