sìdà

the four elements: earth, water, fire, and wind (Buddhism) / the four freedoms: speaking out freely, airing views fully, holding great debates, and writing big-character posters, [[大鳴大放|大鸣大放<dàmíngdàfàng>]], [[大辯論|大辩论<dàbiànlùn>]], [[大字報|大字报<dàzìbào>]] (PRC)