Definition of back ends:
(n) :
(computing) That part of a hardware or software system that is farthest from the user; the internals rather than the user interface.
(n) :
The rear, back, or unseen portion (of something).
(n) :
(entertainment, etc.) Money paid on a contingent deferred basis, for example, as a proportion of the profits or revenue of a work.
(n) :
The processing of spent fuel from a nuclear reactor into reusable materials.
(n) :
(UK dialectal, Northern England, Scotland) The latter end of any given time, especially the latter part of the year; autumn; late autumn.