If we refer to the dictionary definition of Oracle we find a couple of possible definitions that could be applied to the use made by most people of this term although a couple might lead to some questions.
One which raises a couple of questions is an ambiguous or obscure utterance – not what we want in software testing. The second is a divine communication – very unusual in software testing.
Probably the most relevant one is the which suggests that the person who is delivering wise and potentially influential pronouncements in an orcale. This is the definition that comes closest to the use made of this term in Software Quality Assurance and Quality Control areas. The idea is that the person knows more and can use that knowledge to provide better Quality Control in some fashion.
The issue is that it is only as good as the person making the pronouncement. If they are wrong, then that may lead to a cascade of mistesting and wasted time. The second part is that it is only good as long as the person is in the place where they can claim to be oracular. Once they leave all the information and knowledge goes out the door with them.
Quality Assurance and Process Improvement solves this problem.