This is pretty much a question of the definition you are using.\n\nIn a strict definition, conventional solids have a crystalline structure. Under this definition, glass is a supercooled, highly viscous liquid rather than a conventional (crystalline) solid. \n\nIn many ways, glass acts like a solid. Using that behaviour as a criterion, glass is a solid.
Over hundreds of years, the glass in glass windows sinks down to the bottem.  So is glass a liquid or a solid?