When the word pioneer was first introduced into the English language in the early sixteenth century, it was a specific military term for an infantryman tasked with going ahead of the army to clear terrain and dig trenches, and the modern definition emerged from a seventeenth-century sense of "explorer" or generally "one who does things first". The term comes from French pionnier, meaning "foot-soldier", and that traces to the Old French word peon, which is also the source of the English words pawn and peon. Going back further, we can trace pioneer to the Medieval Latin noun pedonem, still meaning "foot-solider". The root there is pes, which is reconstructed to the Proto-Indo-European root ped, "foot" (this is etymon of a lot of English words, including pajama, pedigree, podium, impede, and pilot).
Hello! I'm Adam Aleksic, a sophomore studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy politics, vexillology, geography, board games, conlanging, and law.