ap·pli·ca·tion / ˌapliˈkāshən/ • n. 1. a formal request to an authority for something: an application for leave. ∎ the action or process of making such a request.2. the action of putting something into operation: the application of general rules to particular cases. ∎ practical use or relevance: this principle has no application to the present case.3. the action of putting something on a surface: a fresh application of makeup. ∎ a medicinal substance put on the skin.4. sustained effort; hard work: the job takes a great deal of patience and application.5. Comput. a program or piece of software designed and written to fulfill a particular purpose of the user: a database application.DERIVATIVES: ap·pli·ca·tion·al / -shənl/ adj. .