(glas, gläs) noun
1. A hard, amorphous, brittle, usually transparent substance made by fusing one or more of the oxides of silicon, boron, or phosphorus with certain basic oxides, followed by rapid cooling to prevent crystallization. ♦ Collateral adjectives: hyaline, vitreous. Principal types are:
—borosilicate glass
A tough optical and thermal glass; Pyrex glass.
—bottle glass
A soda-lime-silica glass with a greenish color caused by iron impurities.
—crown glass
Hard optical sodium-silicate glass of low refraction.
—cut glass
Glass ornamented by cutting or grinding on a wheel of stone, iron, or wood into grooves, leaving prismatic or crystal-like elevations between them.
—flint glass
Soft optical lead-oxide glass of high refraction.
—ground glass
Glass having a smooth, semi-opaque surface that diffuses light.
—lime glass
Plate, window, and container glass; made of lime and soda.
—milk glass
Opaque milky glass containing cryolite.
—optical glass
High-quality glass specialized in refractive and dispersive powers for lenses.
—plate glass
Sheets of glass poured, rolled, and polished: used for mirrors and display windows.
—safety glass
Glass in two sheets enclosing a film of transparent adhesive plastic tightly pressed between them; laminated glass: often called shatterproof glass.
—stained glass
Glass colored by the addition of pigments in the form of metallic oxides: used decoratively, as for church windows.
—window glass
Ordinary blown glass, flattened from cylinder shapes.
—wire glass
Glass sheets reinforced with wire netting.
2. Any fused substance resembling glass.
3. Any article made of glass, as a window pane, a goblet or tumbler, a mirror, spectacles, etc.
4. A telescope; also, a barometer.
5. A glass devised for measuring time by the passage of sand or the like through an orifice. See HOURGLASS.
6. The contents of a glass or drinking vessel: He drank a glass of wine.
7. Glassware collectively.
—v.t.
1. To enclose with glass.
2. To reflect; mirror.
3. To give a glazed surface to.
—adjective Made of, relating to, or like glass. [OE glœs]
Glass may appear as a combining form in hyphemes and solidemes, or as the first element in two-word phrases; as in:

(glas, gläs), Carter,
1858–1946, U.S. statesman.