From Geoffrey Hunter's Metalogic, p.5:
... a thing is an English word only if it has meaning.
At this point I stopped reading the textbook, and thought to myself: "Is this really so?". NB: I don't care about English in particular, but about natural languages in general.
I feel there are two major points that need elaborating: (a) What is a word? How does a thing become a legitimate word of a given language? (b) What is meaning, and in what sense can words "have" it?
My best current thoughts:
(a) Words, in a very crude sense, can be taken as sounds uttered or, if the word is written, as a pronounceable string of characters. A word can be coined, after which it is undoubtedly a legitimate word of the language – this is something I think we can all agree on. More on words becoming legitimate in (b).
(b) This is too broad for me to handle because it comprises most part of my question. The best I can do is mention Lewis Carroll's poem Jabbererwocky and say that that there are many words in it that are not being coined (at least intentionally), nor is there any intended meaning behind the words whatsoever. Does the use of these words make them legitimate words of English? One can make the case that Lewis Carroll's literary works (the ones about Alice) are very popular and influential and are part of not only the cultures of English-speaking countries, but lots of other cultures as well, giving him a "licence" to make up words with no intended meaning and make them legitimate words (at least of English). Can I, an average person whose native language is English, utter or write down a word without any intended meaning and truthfully say that the word is now a legitimate word of English (i.e. saying so makes it so)?
Question: what does leading work in philosophy of language has to say on these matters? Keep in mind that the central question I'm asking is the one in the question's title.