Application programming interface
An application programming interface or API is that little gobbet of code that lets you hook one software application, database, etc, with another. Especially useful when importing and exporting data. So if you’re in SharePoint and you want to look up into the client static data system, which is operating on a steam-powered mainframe designed by Charles Babbage, what you will need is an API (but save your breath: one won’t exist and it will take the IT department, by their own self-interested assessment, 600 person hours to create one).
Jeff Bezos famously insisted on one long across his whole organisation, on pain of instant dismissal, long before they were fashionable, and the rest is history.