A single item is an individual object or thing that is not part of a larger group. It can be anything from a physical object, such as a book, to an intangible concept, such as a thought or idea. A single item can also refer to a single unit of measurement, such as a pound or a gallon. In some cases, a single item may be part of a larger set, such as a single piece of furniture in a room full of furniture. The term 'single item' is often used to describe something that is unique or stands out from the rest.