Where does “ἅπαξ λεγόμενον” come from?

ἅπαξ λεγόμενον (Ancient Greek) comes from Ancient Greek ἅπαξ, from Proto-Indo-European sm̥-, from Proto-Indo-European sem- — together, one.

Ancestry of “ἅπαξ λεγόμενον”, step by step

StepLanguageWordMeaning
1Ancient Greekἅπαξonce, one time, only once
2Proto-Indo-Europeansm̥-one; with, together
3Proto-Indo-Europeansem-together, one

Words derived from “ἅπαξ λεγόμενον”

Every word from Proto-Indo-European sem- →Every word from Proto-Indo-European sm̥- →Every word from Ancient Greek ἅπαξ →