Noncrystalline
Noncrystalline refers to materials that do not have a regular, repeating atomic structure. These materials lack the ordered arrangement of atoms found in crystalline substances, resulting in a lack of a defined melting point and a tendency to be amorphous or glassy in nature. Noncrystalline materials may exhibit properties such as isotropy, where their physical properties are the same in all directions, and may include substances such as glass, gels, and certain polymers.