glæs

Old English glæs comes from Proto-Germanic *glasą, possibly from *glōaną (to glow, to shine). If this etymology is correct, glass was named for its luminous quality — the way it catches and transmits light. The word is cognate with Old High German glas (glass), Old Norse gler (glass), and Dutch glas. The Germanic word may have originally referred to amber (also glowing, also translucent) before being transferred to the manufactured material.

Glass was first manufactured around 3500 BCE in Mesopotamia and Egypt — initially as beads and small vessels. Roman glassblowing, developed around the first century BCE, revolutionized production. Blown glass was faster to make, thinner, and more varied in shape than earlier techniques. Roman glass reached every corner of the empire. The word glæs entered Old English naming a material that Roman technology had already made commonplace.

The medieval stained glass window is glass's most dramatic cultural achievement. Chartres Cathedral (1194-1220), Sainte-Chapelle (1238-1248), and York Minster contain windows that have transmitted colored light for eight hundred years. The glass has not degraded. It has not faded. The material's chemical stability is so extreme that medieval glass is used as a reference standard for long-term material preservation.

Modern glass is everywhere and invisible. Window glass, screen glass (Corning's Gorilla Glass protects billions of smartphones), fiber optic glass, laboratory glass, glass bottles. The material that was once precious enough to simulate gemstones is now so common that breaking it is a minor nuisance. The glow-word names the most transparent substance in daily life — the material whose purpose is to not be seen.