It seems solid to me, but to a physicist this is a valid question. Glass is one of the
As water cools to its freezing point, it crystallizes into ice. When glass cools from a hot liquid, it slows down but never crystallizes. Researchers at Emory University have studied the phenomenon for years, but have yet to find a definitive answer, which could greatly impact the science of nanotechnology. Link
"squishy" substances that cannot be pinned down as a solid or liquid. Referred to as "soft condensed materials," they include everyday substances such as toothpaste, peanut butter, shaving cream, plastic and glass.
As water cools to its freezing point, it crystallizes into ice. When glass cools from a hot liquid, it slows down but never crystallizes. Researchers at Emory University have studied the phenomenon for years, but have yet to find a definitive answer, which could greatly impact the science of nanotechnology. Link