As far as I can recall, the flight review has always been a flight review. Common useage has put it as "BFR," but it's never been specifically called a Biennial Flight Review by the regulation.
Common useage of the term as Biennial points to the 24 month limitation imposed by 61.56(c). In this respect the term is correct in defining the type of review (as opposed to other reviews required under the FAR); it adds specificity to the reference, and instantly gives recognition to the term. However, you are correct; the reference in the FAR is to flight review, not biennial flight review.
You must look closely at the language used in other areas, too. Pilots often refer to IMC when referencing the FAR, but find it in the FAR. It's not there. It's found in only one place, and a location most pilots will never see.
Look at the term FAR, itself. This doesn't apply to the Federal Aviation Regulations, which are actually found under Title 14 of the Code of Federal Regulations. FAR is an acrynym reserved in the CFR for Federal Aquisition Regulation, and is assigned to the General Services Administration. Therefore, the use of FAR, when referencing the Federal Aviation Regulation, is also incorrect.
However, the common useage of the term in this industry is appropriate simply because it is so well understood as pertaining to the aviation regulations specified in 14 CFR Parts 1-1199. (Specifically, the common useage of the term refers to only to parts 1-199).
VMC and VFR are commonly used interchangably, where in reality, they are not. Likewise for IFR and IMC.
Pilots frequently refer to their pilot license. However, the FAA doesn't issue licenses; they issue certificates.
Instructors frequently refer to the CFII as though it were a separate certificate. In reality, that designation refers to a single certificate, the flight instructor certificate. It indicates that the holder has been issued a flight instructor certificate with an instrument rating. There is no such thing as the holder of a CFI, CFII, and MEI. In such a case, the holder posseses one certificate, with several ratings. However, common useage of the separate referencs CFII and MEI often serve to quickly clarify the ratings a certificate holder may posses.
There is no such thing as an A&P. There is such thing as a person holding a Mechanic certificate, with airframe and powerplant ratings. However, it's often faster, and just as well understood, to refer to a mechanic with both ratings as an A&P. Frequently a mechanic will be called an A&P even though he or she may not hold both ratings, because most folks wouldn't have a clue if someone said, "I'm seeing my A this afternoon for an inspection," or "I need to make an appointment to see my P." Therefore the common useage "A&P"is standard.
The same can be said for an IA. In reality, the holder of an inspection authorization is actually the holder of a Mechanic certificate with both Airframe and Powerplant ratings, who holds inspection authorization. That's too much to mumble, so we all say "IA," and understand what it means.
Often we intermingle the useage of PIC, referring to the logging of PIC, and the acting of PIC, as the same thing. In reality, they are not.
The list is endless. Numerous cases exist of common useage of terms, which are not technically correct. However, aviation has it's own language, and it's a commonly understood language. Such useage has a place in the industry. I wouldn't be too quick to bounce a job applicant simply because he or she talks like a pilot.