A word must not necessarily be in use in order “to be”.
Language is not confined to words in use or as historical components. As long as there are rules for prefixes and suffixes or roots which imply yet more possible forms there will eventually be users of those extensions.
Kierkegaarde used the word stentoriousness.
Perhaps he was the first to do so.
Perhaps he was the last.
Perhaps he was compelled to speak stentoriously.