A cactus (pl.: cacti, cactuses, or less commonly, cactus) [3] is a member of the plant family Cactaceae (/ k æ k ˈ t eɪ s i. iː,-ˌ aɪ /), [a] a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. [4] The word cactus derives, through Latin, from the Ancient Greek word κάκτος (káktos), a name originally used by Theophrastus for a spiny plant ...