Although not a medical term per se, we use the word [vernacular] constantly on this blog to refer to terms used commonly or colloquially by non-health care professionals.
Merriam-Webster’s definitions of [vernacular] are multiple, all pointing to common usage by a group:
• of, relating to, or using the language of ordinary speech rather than formal writing
• of, or relating to the common style of a particular time, place, or group
• using a language or dialect native to a region or country rather than a literary, cultured, or foreign language
• of, relating to, or being a nonstandard language or dialect of a place, region, or country
• of, relating to, or being the normal spoken form of a language
• applied to a plant or animal in the common native speech as distinguished from the Latin nomenclature of scientific classification
This last definition is the one that applies mostly to what we mean in this blog. While we may use the anatomical term “rectus abdominis” , most people would say “six-pack” – which is wrong on two aspects: it is vernacular, and it is not a “six pack”, if you count them, you will see that a well-developed rectus abdominis has eight bellies, four on each side, making it really an “eight pack”!
Another one would be the vernacular term "pinky" to refer to the fifth digit of the hand. Yet another one would be the use of the vernacular term “stomach” to refer to the abdomen, that is one of my pet peeves!