A word is a word before it gets put in the dictionary. A dictionary is a subset of the language. You cannot prove something isn't a word by showing that it is n

A word is a word before it gets put in the dictionary. A dictionary is a subset of the language. You cannot prove something isn't a word by showing that it is not in the dictionary, but if its in the dictionary, then it is definitely a word (unless it's a lexicographical error).