Hapax legomenon is an interesting expression I encountered one evening, a while ago, whilst reading Current World Archaeology magazine. Sometimes, I get the opportunity for a quiet read.
The expression hapax legomenon turns out to be derived from the Classical Greek ἅπαξ λεγόμενον, meaning something that is said only once. Not like Michelle of the Resistance Dubois in "Allo Allo", with her "I shall say this only once..." but in a body of literature.
Hapax legomenon appeared, in fact, in a book review. The book is Latrinae Et Foricae: Toilets in the Roman World.
It turns out that in all of the ancient literature that is still known, the word foricae appears only once. It was mistranslated as "bowel" for a long time, but actually means a multi-seat public toilet with no dividing walls. Here is a picture of a famous one I saw in Phillipi.
And the Hapax LEGOmenon forica is like this...