Cactus

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early 17th century (in the sense ‘cardoon’): from Latin, from Greek kaktos ‘cardoon’.

wiktionary

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From Latin cactus, from Ancient Greek κάκτος(káktos, “cardoon”), possibly of pre-Greek origin.

etymonline

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cactus (n.)

c. 1600, in a classical sense, "cardoon, artichoke," from Latin cactus, from Greek kaktos, name of a type of prickly plant of Sicily (the Spanish artichoke), a "foreign word of unknown origin" [Beekes]. In reference to the green, leafless, spiked American plants from 1769, because Linnaeus gave the name to them thinking they were related to the classical plant. Related: Cactal.