Spinach is quite the well-traveled word. The earliest it can be traced to is the Anglo-Norman word spinache, which in turn comes from the Old French term espinache. At this point we get involved in the history of the word itself: since spinach was first introduced in the Provence region of France, the word can be traced through the local language of Provencal French, where it took the form of espinarc. Since the vegetable was introduced to Europe by the Arabs, the etymology next goes back to Arabic, as isbanakh. Finally, since Spinach is suspected (by horticulturists) to have originated in that area treading the line between the Middle East and Central Asia, we can trace the word further eastward. The word didn't change much as it went back to Persian ispanakh, from Proto-Iranian spai. You might be noticing a lack of semantic change here; the morpheme was just associated with spinach for a very long time. That changes with the Proto-Indo-European term spei, meaning "thorn-like", and we can go no further.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.