The OED keeps track of original usage. Here's the entry: orig. U.S. A business or enterprise that is in the process of starting up, or that has just been estab

The OED keeps track of original usage. Here's the entry: orig. U.S. A business or enterprise that is in the process of starting up, or that has just been established; a startup company, venture, etc. They cite these early usages in print: 1975 Chicago Defender 20 Sept. 23/1 The many problems faced by any new start up, but most assuredly by a black financial institution. 1986 Your Business Mar. 11/3 There are the small businesses; the heroic little start-ups in their garages and garden sheds.