In philately, the abbreviation signifies a postage stamp that has never been hinged or mounted, retaining its original gum. Such a stamp is considered to be in perfect, unused condition, as issued by the postal authority. An example would be a stamp carefully preserved in pristine condition since its purchase.

Stamps in this superior condition are often more valuable to collectors, particularly for older or rarer issues. Maintaining original gum is a key factor in assessing a stamp’s quality and potential appreciation. Historically, hinging was a common practice, making unhinged examples from earlier periods relatively scarce and thus more desirable. This careful preservation contributes significantly to a collection’s overall worth and prestige.