“Al dente” is one of those terms that drives me crazy. It means “to the tooth”, and it’s used to describe the ideal amount of cooking for pasta.
However, there’s little in the term that tells you where that is. I’ve heard it used to describe pasta that I consider under cooked as well as pasta that I consider properly cooked. Perhaps there are greater subtleties that have eluded me, but that only adds to my dislike of the term.
Singing is full of these terms. These are terms that are code words for something that is hard to describe. “Head voice”, “chest voice”, “on the breath”, “legato”, “support” and so on all contain clues to what they describe, but once you move past those clues, they start breaking down in their specifics and precise meaning to individuals.
This is the part where I should provide an answer to this problem, but I don’t have one. Perhaps the answer is acknowledging that there is a problem, and these terms don’t have universal meaning between singers and singing teachers.