If you use mind as an undefined word, then of course, words are easily definable. If by the use of the word mind, you are referring to some specific thing, the

If you use mind as an undefined word, then of course, words are easily definable. If by the use of the word mind, you are referring to some specific thing, then me defining what you refer to is simply restating your definition of that thing. Most conversation of mind thus end up in semantic debates or system of beliefs. Like you say, until we can objectively observe a representation of the self in the brain, and label it mind, then the mind isn't a real thing. Now you can imagine a thing which you have not observed, believe it to exist, and call it mind. That's where you start debating beliefs, which is a futile exercise. I thus like to define the mind as the subset of my brain which generates my inner voice. And the self is the set of things my mind groups under it, for example when I say "I". Self is thus a moving target defined by my mind. Mostly an imaginary construct therefore.