ə.ˈkɹi.ʃən ə.ˌkjuːm.jə.ˈleɪ.ʃən (law) an increase in a beneficiary's share in an estate (as when a co-beneficiary dies or fails to meet some condition or rejects the inheritance) an increase by natural growth or addition (geology) an increase in land resulting from alluvial deposits or waterborne sediment (biology) growth by addition as by the adhesion of parts or particles (astronomy) the formation of a celestial object by the effect of gravity pulling together surrounding objects and gases something contributing to growth or increase he scraped away the accretions of paint the central city surrounded by recent accretions