A term used with early AI applications, known as "expert systems." Today, "inference" without the "engine" is commonly used to refer to the software that generates answers for the user. However, inference engine is occasionally used, and it is a more accurate term because "engine" implies software, which is what inference is.
Human Rules Were the First AI
In the 1960s, an AI was an "expert system" that relied on rules defined by people. Expert systems were also one application, not so sharply divided into model training and inference as they are today. See
expert system.