1. A black box is a device, system or object which can be viewed in terms of its inputs and outputs, without any knowledge of its internal workings. Its implementation is "opaque". Almost anything might be referred to as a black box: a transistor, an algorithm, or the human brain.
2. Device, process, or system, whose inputs and outputs (and the relationships between them) are known, but whose internal structure or working is not well, or at all, understood, not necessary to be understood for the job or purpose at hand, or not supposed to be known because of its confidential nature.
https://en.wikipedia.org/wiki/Black_box (1.); http://www.businessdictionary.com/definition/black-box.html (2.)
Author: Anja Muskowitz