[Stefano]

There is no official "Car Guy" dictionary. Some terms are defined in value guides such as NADA or CPI etc.

Courts are often called upon to define terminology in a given context.

"Original Engine" can be interpreted to mean "Original" to that make and model. An example would be one with a correct date and suffix code, but no VIN.

Some cars from the 1960s did not have VINs stamped on any of the drive train components.

I often use "original Born with engine" to clear up any potential misunderstandings.