late 14c., "the seven virtues personified;" early 15c., "the Pleiades" (see Pleiades), seven daughters of Atlas and Pleione, placed among the stars by Zeus and popularly known as the Seven Stars (see seven).
In late 20c. applied to seven venerable and prestigious U.S. colleges for women only: Barnard, Bryn Mawr, Mount Holyoke, Radcliffe, Smith, Vassar, and Wellesley. The phrase also was applied to seven similar cannon used by the Scots at Flodden. As a late-20c. name for the major multi-national petroleum companies, Seven Sisters is attested from 1962. They were listed in 1976 as Exxon, Mobil, Gulf, Standard Oil of California, Texaco, British Petroleum, and Royal Dutch Shell.
updated on July 01, 2022