Defining terms may seem dull and unnecessary, and most of the time it is - we don't have to define every term we use (that would be mad...) - but to simply and quickly define the term under discussion can save a lot of misunderstandings and frustration. It's as simple as, "I'd like to discuss X, by which I mean "DEFINITION," do you agree?" "Yes, that seems fine." "Okay then, X is..." etc., etc.
Also, thank you for introducing me to the word "copacetic," which I am now itching to use!