An uncountable noun is a type of noun that cannot be counted individually. These nouns represent things that are seen as a whole or mass, such as water, sand, or information. They do not have a plural form and are typically used with singular verbs. For example, we say "The water is cold," not "The waters are cold." Uncountable nouns often refer to substances, concepts, or collective categories. Common examples include music, happiness, and furniture. When using uncountable nouns, we often quantify them with words like "some," "much," or "a little," rather than numbers.