accretion
/əˈkriːʃn; ə`kriʃən/ n 1 [U] (a) growth or increase by means of gradual additions （逐渐地）生长, 增大. (b) the growing of separate things into one 连生; 合生. 2 [C] (a) added matter that causes such growth 增添物. (b) thing formed by the addition of such matter 积累而成的东西: a chimney blocked by an accretion of soot 被聚积的煤烟子所堵塞的烟囱.
