Popularity is what makes a definition “good.” Language is subjective.
Are you going to offer more than pure ipse dixit to back that up? Because language being “subjective” (it’s intersubjective, not quite the same…) does not even come near to justifying such a proposition. What the hell does that even mean? Do you take a poll and then decide, oh look, X many people think such and such a word means this or that, therefore the definition is good? Come to think of it, since language is “subjective” how do you even ascertain what the definition is?
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That’s exactly what you do, although not in so many words. That’s what language textbooks teach: how words are commonly used. As definitions change over time, language changes.
What do you propose it is that makes a definition “good”?
There is a non-arbitrary construct which is logically and materially equivalent to language, for which certain rules, norms and usages are appropriate. Others are not. If one uses English words without reference to grammar, or calls things by names other than some range of intentional phenomena that person is not speaking English. Whatever concept he identifies as ‘English’ is, by demonstration of action, not the same as ours. Likewise, such a person would performatively be not speaking English, because making sense most of the time to other English speakers, and the capacity for correct communication, are part of the actual practice and conceptual meaning of ‘speaking English’. Anyone failing in these systemic ways would simply not be speaking English, from our perspective either. It would be ‘making sounds, some of which we use for expressions in English’.
This is a way that transcends the usual existential/empirical/metaphysical arguments around language, it is intersubjective but subjectivity is omnipresent in all the actual meanings of logic, inferences, though, concepts, language; nonetheless there is a nontrivial ability to speak of reality and practical reality is identical, and understand what the correlation of one to the other is. Which is simply to say, logic is non-arbitrary..