Real Dictionary

saguaro in American English
a giant cactus (Carnegiea gigantea) with a thick, spiny stem and white flowers, native to the SW U.S. and N Mexico
noun: a tall, horizontally branched cactus, Carnegiea (or Cereus) gigantea, of Arizona and neighboring regions, yielding a useful wood and bearing an edible fruit: still locally common, though some populations have been reduced

saguaro in British English
noun: a giant cactus, Carnegiea gigantea, of desert regions of Arizona, S California, and Mexico, having white nocturnal flowers and edible red pulpy fruits