(noun)
a hard and often-brittle material, usually transparent or translucent, created by mixing silicates with other substances, used to make windows and various utensils;
e.g. A light bulb is made of glass, so it will break if you drop it.
(noun)
broadly things made of such a material, such as eating utensils or the flat sheets used to make greenhouses;
e.g. The store keeps its glass in a special cabinet so that customers do not accidentally break things. In the winter, some fruits may be grown under glass so that they are not damaged by the cold.
(noun)
a container from which a beverage may be drunk, typically made of glass, or the amount of a liquid that can be held by such a container;
e.g. He filled a glass with orange juice to drink with his breakfast. I like to drink a glass of water as soon as I wake up in the morning.
(noun)
(British) a mirror, a reflective surface often used to look at one's own appearance;
e.g. She stood in front of the glass to style her hair.
(verb)
to build walls or casing around something using glass, in order to enclose or otherwise cover it;
e.g. They decided to glass their porch to keep dust and bugs out.