The noun "glass" can be both countable and uncountable.
Meaning: the material used to make windows, bottles, fishbowls, etc.
Example sentence: Milk used to be sold in glass bottles, but now it comes in plastic containers.
Meaning: a drinking vessel made of glass
Example sentence: My daughter knocked over a glass of milk and it spilled all over the table.
Test your understanding:
- The glass they poured my beer into was cracked, so I didn't drink it.
- The glass in this window is cracked, so we should replace it.