Nouns which may be used in grammaticallyuncountable senses. Anuncountable noun, also known as amass noun ornon-count noun, typically refers to a substance or an abstraction, is grammatically singular, and is generally not used with indefinite articles (a oran) or numbers. If it is so used, the meaning shifts to mean roughly “a kind of” the underlying substance. Many nouns have both countable and uncountable senses. Nouns' senses are assumed countable unless specifically marked uncountable.
For example,glass, as a substance, is uncountable. We sayglass is breakable. A phrase likeseveral glasses inthis bottle is made of several glasses means “this bottle is made of several different kinds of glass.” On the other hand,a glass orseveral glasses normally refers to drinking vessels made of glass, which is a separate, countable sense ofglass.