Glass is actually :

Glass is scientifically defined as an amorphous solid that lacks the long-range atomic periodicity found in crystalline solids [t4][t7]. It is formed through a process called vitrification, which occurs when a liquid is supercooled rapidly enough to bypass crystallization [t1][t8]. During this transition, the material retains the disordered molecular arrangement of a liquid but acquires the mechanical rigidity of a solid [t6]. Consequently, glass is often described as a 'vitrified liquid' or a 'supercooled liquid' because it exists in a metastable state where molecules are 'frozen' in a disordered pattern [t6]. Unlike crystalline solids, glass does not have a sharp melting point but instead undergoes a gradual glass transition [t1][t2]. While it exhibits solid-like behavior, its structural nature is that of a liquid that has lost its fluidity due to extreme viscosity [t1][t6].

Sources

1. [1] https://en.wikipedia.org/wiki/Glass_transition
2. [2] https://www.sciencedirect.com/science/article/pii/S0079642523000166
3. [3] https://www.sciencedirect.com/topics/materials-science/glass-formation