numeral · four major; four great; four supreme (items, people, or works)

《西游记》是四大名著之一。

the four elements in Buddhism: earth, water, fire, and wind

佛教认为世界万物皆由四大和合而成。

the four political freedoms in the PRC: speaking out freely, airing views fully, holding great debates, and writing big-character posters

文革期间，所谓的“四大”对当时社会造成了深远的影响。