back end

noun back ends · back-end · backend · backen' · back-en'

1. The rear, back, or unseen portion (of something). The back end of the operation is kept out of sight of the customers.
2. That part of a hardware or software system that is farthest from the user; the internals rather than the user interface. Together, the MathDocument and PaperController classes comprise the MathPaper application's front end, while the Evaluator makes up the application's back end. This technique of having separate front and back ends is a common […]

   Opposite: front end

3. Northern England, Scotland, UK, dialectal The latter end of any given time, especially the latter part of the year; autumn; late autumn. I'll see you on the back end of tomorrow.
4. usually Money paid on a contingent deferred basis, for example, as a proportion of the profits or revenue of a work. so-called “back end” deals is speculative at best. Ideally, the author or book publisher will secure a percentage of gross revenues rather than net profits, but such deals are rare indeed.
5. The processing of spent fuel from a nuclear reactor into reusable materials.