- The definition of an app is short for application and is software for use on a smart phone or computer.
An example of an app is the Yelp app for the iPhone.
Origin of appShort for application.
app - Computer Definition
(1) (APPlication) The file extension for executable Mac applications. See APP file.
(2) (APPlication) The term has been shorthand for "application" in the IT community for a long time. However, it became popular with the consumer for mobile applications in smartphones and tablets after Apple debuted the iPhone 3G in 2008. It is just as correct to say "iPhone application" as it is "desktop computer app;" although app is shorter, and computer people love to abbreviate. See application and online app store.
(3) (APPlication) In the engineering world, an app can refer to a circuit design, using the word "application" in the context of purpose. For example, "high-voltage apps" means high-voltage circuit designs. The term predates mobile software apps by decades.