From Greek 'kaktos' (a spiny Mediterranean plant) — European botanists applied it to New World succulents they resembled.
A succulent plant with thick stems, typically bearing spines and found in arid regions.
From Latin 'cactus' (a prickly plant of Sicily), borrowed from Greek 'kaktos' (a prickly plant of Sicily, possibly the cardoon or artichoke thistle). The Greek word is of uncertain etymology; it may be a pre-Greek Mediterranean substrate word, possibly connected to Semitic languages given the plant's range, or possibly from a lost Sicilian dialect word. The 18th-century botanist Carl Linnaeus applied the name to the New World succulent family Cactaceae, transferring
The original Greek 'kaktos' referred to a completely different plant — the name was transferred across an ocean.