(or四空天)catur-ārūpya brahmalokas; also 四無色界 and see 四空定. The four immaterial or formless heavens, arūpa-dhātu, above the eighteenbrahmalokas: (1) 空無邊處ākāśānantyāyatana, also termed 虛空 處 the state or heaven of boundless space; (2) 識無邊處vijñānanāntyāyatana, of boundless knowledge; (3) 無所有處 ākiñcanyāyatana, of nothing, or nonexistence; (4) 非想非非想處naivasanjñānasañjnāyatana, also styled 非有想非無想 the state of neither thinking nor not thinking (which may resemble a state of intuition). Existence in the first state lasts 20, 000 great kalpas, increasing respectively to 40, 000, 60, 000 and 80, 000 in the other three.