heaping up, gathering, accumulation, heap. As t.t. with ref. to kamma “conservation”, with ref. to body & form “integration” (See discussion & defin. at; Cpd. 253; Dhs trsl. 195). DN.i.76 (= odana = kummās’ûpacayo, see under kāya) Dhs.582, Dhs.642 (rūpassa u. = āyatanānaṃ ācayo), Dhs.864 Vb.147, Vb.151 sq.; Kv.520; Ne.113; Vism.449; DN-a.i.220; Pv-a.198 (but variant reading paccayassa preferable).

fr. upa + ci, cp. caya & ācaya