Polymorphism
From Online Dictionary of Crystallography
Polymorphisme (Fr). Polymorphie (Ge). Polimorfismo (It). 多形現象 (Ja). Полиморфизм (Ru). Polimorfismo (Sp).
The phenomenon in which the same chemical compound exhibits different crystal structures. As an example, CaCO3 may crystallize as trigonal calcite or orthorhombic aragonite.