Cactus n. : Any plant of the order Cactacae, as the prickly pear and the night-blooming cereus. See Cereus. They usually have leafless stems and branches, often beset with clustered thorns, and are mostly natives of the warmer parts of America.

Example:
Where can I find a Cactus pot that is two parts of male genitals?

Taxonomy
cactus, species, columnar cacti, plants, stems, succulent, flowers, cactus flowers, leaves, genus, transpiration, diameter, Cactaceae, the leaves, spines, family, cactus species, moisture.

Defination from the web:
cactus species are night blooming, as they are pollinated by nocturnal insects or small animals, principally moths and bats. ... The cactus family is endemic to the Americas with one exception, Rhipsalis baccifera; this species has a pantropical distribution, occurring in ...