(n.) the act of revealing something, or making it public
Patefaction is the act of revealing or disclosing something; to patefy, likewise, is to make something known or clear.
First used in English in the sixteenth century, patefaction derives from a Latin word, patere, literally meaning “to open”, and it’s this sense of casting something open so that all can see or appreciate it that has been carried through to the word today.
That makes patefaction an etymological cousin of the adjective patent, as in “patently obvious”, as well as a clutch of less familiar words like patulous (“gaping open, expanded”) and patible, the horizontal bar of a crucifix (in the sense that it forcibly “opens” a victim’s arms). The humble patio might be a distant relative of patefaction too (although a more liekly theory is that it comes to us from an unrelated Provençal word meaning “communal land”).
Besides their etymologies, a clear sense of openness and exposure still connects these words in English today.