A glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle, and often optically transparent. Glass is commonly used for windows, bottles, modern hard drives and eyewear; examples of glassy materials include soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovy-glass, and aluminium oxynitride. The term glass developed in the late Roman Empire. It was in the Roman glassmaking center at Trier, now in modern Germany, that the late-Latin term glesum originated, probably from a Germanic word for a transparent, lustrous substance.