noun (pl. hapax legomena or hapaxes)
A word that appears only once in a text corpus or body of writing—be this a particular author's oeuvre, a
work of substantial length, or a language's entire collection of writing, including the Twittersphere.
From Ancient
Greek hápax legómenon ("
thing once said").
The old Ottoman Governments regarded this
clan of manticratic peers with a mixture of reverence and distrust.
—T. E.
Lawrence, 1926
Despite the constant negative press covfefe
—Donald Trump producing a hapax legomenon of his own,
2017