polycrystalline

poly- +‎ crystalline

polycrystalline (comparative more polycrystalline, superlative most polycrystalline)

1. Composed of an aggregate of very small crystals in random orientations
   • 1966, Proceedings of the Seventh International Conference on Phenomena in .in Ionized Gases:

     This was revealed only in the experiments of ion bombardment of single crystals, because a polycrystalline material, even though its microcrystallites have a regular structure, in fact behaves like a nonarranged, random system.

• polycrystalline silicon

• polycrystal