From Longman Dictionary of Contemporary Englishcactuscac‧tus /ˈkæktəs/ noun (plural cacti /-taɪ/ or cactuses) [countable] 
HBPa desert plant with sharp points instead of leaves
HBPa desert plant with sharp points instead of leavesExamples from the Corpus
cactus• It is a perfect location for a cactus.• But once in place, a cactus is unlikely to remain a solitary specimen for long.• Such glass fittings include mixing coils and cactus fittings.• If he were a plant, he'd be an exotic cactus.• So are the other varieties of native cactus and most of the desert trees.• She found the rabbit, chewing on a stubby cactus, and stabbed it in the neck.• Clearly, the cactus never dies out completely, nor do the moths.• As for water, that would come in minute drops from the cactus.Origin cactus (1700-1800) Latin thistle-like plant, from Greek kaktos 