concretion (n.)

c. 1600, "act of growing together or uniting in one mass;" 1640s, "mass of solid matter formed by growing together or conglomeration," from French concrétion (16c.) or directly from Latin concretionem (nominative concretio) "a compacting, uniting, condensing; materiality, matter," from concretus "condensed, congealed" (see concrete (adj.) ). Related: Concretional; concretionary.